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# Intro to data processing
### Jakub Nowosad <br><a href="mailto:nowosad.jakub@gmail.com">nowosad.jakub@gmail.com</a>
### 2017-04-24

---




## Dataset


```r
library('gapminder')
```

or


```r
gapminder &lt;- readRDS('data/gapminder.rds')
```

http://www.gapminder.org/data/

http://github.com/jennybc/gapminder

http://www.youtube.com/watch?v=jbkSRLYSojo

---
# Vectors - indexing

- empty index - `[ ]`
- positive index - `[5]`
- zero index - `[0]`
- negative index - `[-1]`
- logical index - `[x&gt;5]`
- name index - `["country"]`

---
## data.frame - indexing
- A data frame is (at least) a two-dimensional object
- There are many ways to subset a data frame. Some of them are:
    - `[]` operator
    - `$` operator
    - or `subset()` function


```r
head(gapminder)
```

```
##       country continent year lifeExp      pop gdpPercap
## 1 Afghanistan      Asia 1952  28.801  8425333  779.4453
## 2 Afghanistan      Asia 1957  30.332  9240934  820.8530
## 3 Afghanistan      Asia 1962  31.997 10267083  853.1007
## 4 Afghanistan      Asia 1967  34.020 11537966  836.1971
## 5 Afghanistan      Asia 1972  36.088 13079460  739.9811
## 6 Afghanistan      Asia 1977  38.438 14880372  786.1134
```

---
## data.frame - indexing

- `$` operator can be used to retrieve a variable (column) by its name
- The result is a vector


```r
gapminder$country
```

```
##    [1] Afghanistan              Afghanistan             
##    [3] Afghanistan              Afghanistan             
##    [5] Afghanistan              Afghanistan             
##    [7] Afghanistan              Afghanistan             
##    [9] Afghanistan              Afghanistan             
##   [11] Afghanistan              Afghanistan             
##   [13] Albania                  Albania                 
##   [15] Albania                  Albania                 
##   [17] Albania                  Albania                 
##   [19] Albania                  Albania                 
##   [21] Albania                  Albania                 
##   [23] Albania                  Albania                 
##   [25] Algeria                  Algeria                 
##   [27] Algeria                  Algeria                 
##   [29] Algeria                  Algeria                 
##   [31] Algeria                  Algeria                 
##   [33] Algeria                  Algeria                 
##   [35] Algeria                  Algeria                 
##   [37] Angola                   Angola                  
##   [39] Angola                   Angola                  
##   [41] Angola                   Angola                  
##   [43] Angola                   Angola                  
##   [45] Angola                   Angola                  
##   [47] Angola                   Angola                  
##   [49] Argentina                Argentina               
##   [51] Argentina                Argentina               
##   [53] Argentina                Argentina               
##   [55] Argentina                Argentina               
##   [57] Argentina                Argentina               
##   [59] Argentina                Argentina               
##   [61] Australia                Australia               
##   [63] Australia                Australia               
##   [65] Australia                Australia               
##   [67] Australia                Australia               
##   [69] Australia                Australia               
##   [71] Australia                Australia               
##   [73] Austria                  Austria                 
##   [75] Austria                  Austria                 
##   [77] Austria                  Austria                 
##   [79] Austria                  Austria                 
##   [81] Austria                  Austria                 
##   [83] Austria                  Austria                 
##   [85] Bahrain                  Bahrain                 
##   [87] Bahrain                  Bahrain                 
##   [89] Bahrain                  Bahrain                 
##   [91] Bahrain                  Bahrain                 
##   [93] Bahrain                  Bahrain                 
##   [95] Bahrain                  Bahrain                 
##   [97] Bangladesh               Bangladesh              
##   [99] Bangladesh               Bangladesh              
##  [101] Bangladesh               Bangladesh              
##  [103] Bangladesh               Bangladesh              
##  [105] Bangladesh               Bangladesh              
##  [107] Bangladesh               Bangladesh              
##  [109] Belgium                  Belgium                 
##  [111] Belgium                  Belgium                 
##  [113] Belgium                  Belgium                 
##  [115] Belgium                  Belgium                 
##  [117] Belgium                  Belgium                 
##  [119] Belgium                  Belgium                 
##  [121] Benin                    Benin                   
##  [123] Benin                    Benin                   
##  [125] Benin                    Benin                   
##  [127] Benin                    Benin                   
##  [129] Benin                    Benin                   
##  [131] Benin                    Benin                   
##  [133] Bolivia                  Bolivia                 
##  [135] Bolivia                  Bolivia                 
##  [137] Bolivia                  Bolivia                 
##  [139] Bolivia                  Bolivia                 
##  [141] Bolivia                  Bolivia                 
##  [143] Bolivia                  Bolivia                 
##  [145] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [147] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [149] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [151] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [153] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [155] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [157] Botswana                 Botswana                
##  [159] Botswana                 Botswana                
##  [161] Botswana                 Botswana                
##  [163] Botswana                 Botswana                
##  [165] Botswana                 Botswana                
##  [167] Botswana                 Botswana                
##  [169] Brazil                   Brazil                  
##  [171] Brazil                   Brazil                  
##  [173] Brazil                   Brazil                  
##  [175] Brazil                   Brazil                  
##  [177] Brazil                   Brazil                  
##  [179] Brazil                   Brazil                  
##  [181] Bulgaria                 Bulgaria                
##  [183] Bulgaria                 Bulgaria                
##  [185] Bulgaria                 Bulgaria                
##  [187] Bulgaria                 Bulgaria                
##  [189] Bulgaria                 Bulgaria                
##  [191] Bulgaria                 Bulgaria                
##  [193] Burkina Faso             Burkina Faso            
##  [195] Burkina Faso             Burkina Faso            
##  [197] Burkina Faso             Burkina Faso            
##  [199] Burkina Faso             Burkina Faso            
##  [201] Burkina Faso             Burkina Faso            
##  [203] Burkina Faso             Burkina Faso            
##  [205] Burundi                  Burundi                 
##  [207] Burundi                  Burundi                 
##  [209] Burundi                  Burundi                 
##  [211] Burundi                  Burundi                 
##  [213] Burundi                  Burundi                 
##  [215] Burundi                  Burundi                 
##  [217] Cambodia                 Cambodia                
##  [219] Cambodia                 Cambodia                
##  [221] Cambodia                 Cambodia                
##  [223] Cambodia                 Cambodia                
##  [225] Cambodia                 Cambodia                
##  [227] Cambodia                 Cambodia                
##  [229] Cameroon                 Cameroon                
##  [231] Cameroon                 Cameroon                
##  [233] Cameroon                 Cameroon                
##  [235] Cameroon                 Cameroon                
##  [237] Cameroon                 Cameroon                
##  [239] Cameroon                 Cameroon                
##  [241] Canada                   Canada                  
##  [243] Canada                   Canada                  
##  [245] Canada                   Canada                  
##  [247] Canada                   Canada                  
##  [249] Canada                   Canada                  
##  [251] Canada                   Canada                  
##  [253] Central African Republic Central African Republic
##  [255] Central African Republic Central African Republic
##  [257] Central African Republic Central African Republic
##  [259] Central African Republic Central African Republic
##  [261] Central African Republic Central African Republic
##  [263] Central African Republic Central African Republic
##  [265] Chad                     Chad                    
##  [267] Chad                     Chad                    
##  [269] Chad                     Chad                    
##  [271] Chad                     Chad                    
##  [273] Chad                     Chad                    
##  [275] Chad                     Chad                    
##  [277] Chile                    Chile                   
##  [279] Chile                    Chile                   
##  [281] Chile                    Chile                   
##  [283] Chile                    Chile                   
##  [285] Chile                    Chile                   
##  [287] Chile                    Chile                   
##  [289] China                    China                   
##  [291] China                    China                   
##  [293] China                    China                   
##  [295] China                    China                   
##  [297] China                    China                   
##  [299] China                    China                   
##  [301] Colombia                 Colombia                
##  [303] Colombia                 Colombia                
##  [305] Colombia                 Colombia                
##  [307] Colombia                 Colombia                
##  [309] Colombia                 Colombia                
##  [311] Colombia                 Colombia                
##  [313] Comoros                  Comoros                 
##  [315] Comoros                  Comoros                 
##  [317] Comoros                  Comoros                 
##  [319] Comoros                  Comoros                 
##  [321] Comoros                  Comoros                 
##  [323] Comoros                  Comoros                 
##  [325] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [327] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [329] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [331] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [333] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [335] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [337] Congo, Rep.              Congo, Rep.             
##  [339] Congo, Rep.              Congo, Rep.             
##  [341] Congo, Rep.              Congo, Rep.             
##  [343] Congo, Rep.              Congo, Rep.             
##  [345] Congo, Rep.              Congo, Rep.             
##  [347] Congo, Rep.              Congo, Rep.             
##  [349] Costa Rica               Costa Rica              
##  [351] Costa Rica               Costa Rica              
##  [353] Costa Rica               Costa Rica              
##  [355] Costa Rica               Costa Rica              
##  [357] Costa Rica               Costa Rica              
##  [359] Costa Rica               Costa Rica              
##  [361] Cote d'Ivoire            Cote d'Ivoire           
##  [363] Cote d'Ivoire            Cote d'Ivoire           
##  [365] Cote d'Ivoire            Cote d'Ivoire           
##  [367] Cote d'Ivoire            Cote d'Ivoire           
##  [369] Cote d'Ivoire            Cote d'Ivoire           
##  [371] Cote d'Ivoire            Cote d'Ivoire           
##  [373] Croatia                  Croatia                 
##  [375] Croatia                  Croatia                 
##  [377] Croatia                  Croatia                 
##  [379] Croatia                  Croatia                 
##  [381] Croatia                  Croatia                 
##  [383] Croatia                  Croatia                 
##  [385] Cuba                     Cuba                    
##  [387] Cuba                     Cuba                    
##  [389] Cuba                     Cuba                    
##  [391] Cuba                     Cuba                    
##  [393] Cuba                     Cuba                    
##  [395] Cuba                     Cuba                    
##  [397] Czech Republic           Czech Republic          
##  [399] Czech Republic           Czech Republic          
##  [401] Czech Republic           Czech Republic          
##  [403] Czech Republic           Czech Republic          
##  [405] Czech Republic           Czech Republic          
##  [407] Czech Republic           Czech Republic          
##  [409] Denmark                  Denmark                 
##  [411] Denmark                  Denmark                 
##  [413] Denmark                  Denmark                 
##  [415] Denmark                  Denmark                 
##  [417] Denmark                  Denmark                 
##  [419] Denmark                  Denmark                 
##  [421] Djibouti                 Djibouti                
##  [423] Djibouti                 Djibouti                
##  [425] Djibouti                 Djibouti                
##  [427] Djibouti                 Djibouti                
##  [429] Djibouti                 Djibouti                
##  [431] Djibouti                 Djibouti                
##  [433] Dominican Republic       Dominican Republic      
##  [435] Dominican Republic       Dominican Republic      
##  [437] Dominican Republic       Dominican Republic      
##  [439] Dominican Republic       Dominican Republic      
##  [441] Dominican Republic       Dominican Republic      
##  [443] Dominican Republic       Dominican Republic      
##  [445] Ecuador                  Ecuador                 
##  [447] Ecuador                  Ecuador                 
##  [449] Ecuador                  Ecuador                 
##  [451] Ecuador                  Ecuador                 
##  [453] Ecuador                  Ecuador                 
##  [455] Ecuador                  Ecuador                 
##  [457] Egypt                    Egypt                   
##  [459] Egypt                    Egypt                   
##  [461] Egypt                    Egypt                   
##  [463] Egypt                    Egypt                   
##  [465] Egypt                    Egypt                   
##  [467] Egypt                    Egypt                   
##  [469] El Salvador              El Salvador             
##  [471] El Salvador              El Salvador             
##  [473] El Salvador              El Salvador             
##  [475] El Salvador              El Salvador             
##  [477] El Salvador              El Salvador             
##  [479] El Salvador              El Salvador             
##  [481] Equatorial Guinea        Equatorial Guinea       
##  [483] Equatorial Guinea        Equatorial Guinea       
##  [485] Equatorial Guinea        Equatorial Guinea       
##  [487] Equatorial Guinea        Equatorial Guinea       
##  [489] Equatorial Guinea        Equatorial Guinea       
##  [491] Equatorial Guinea        Equatorial Guinea       
##  [493] Eritrea                  Eritrea                 
##  [495] Eritrea                  Eritrea                 
##  [497] Eritrea                  Eritrea                 
##  [499] Eritrea                  Eritrea                 
##  [501] Eritrea                  Eritrea                 
##  [503] Eritrea                  Eritrea                 
##  [505] Ethiopia                 Ethiopia                
##  [507] Ethiopia                 Ethiopia                
##  [509] Ethiopia                 Ethiopia                
##  [511] Ethiopia                 Ethiopia                
##  [513] Ethiopia                 Ethiopia                
##  [515] Ethiopia                 Ethiopia                
##  [517] Finland                  Finland                 
##  [519] Finland                  Finland                 
##  [521] Finland                  Finland                 
##  [523] Finland                  Finland                 
##  [525] Finland                  Finland                 
##  [527] Finland                  Finland                 
##  [529] France                   France                  
##  [531] France                   France                  
##  [533] France                   France                  
##  [535] France                   France                  
##  [537] France                   France                  
##  [539] France                   France                  
##  [541] Gabon                    Gabon                   
##  [543] Gabon                    Gabon                   
##  [545] Gabon                    Gabon                   
##  [547] Gabon                    Gabon                   
##  [549] Gabon                    Gabon                   
##  [551] Gabon                    Gabon                   
##  [553] Gambia                   Gambia                  
##  [555] Gambia                   Gambia                  
##  [557] Gambia                   Gambia                  
##  [559] Gambia                   Gambia                  
##  [561] Gambia                   Gambia                  
##  [563] Gambia                   Gambia                  
##  [565] Germany                  Germany                 
##  [567] Germany                  Germany                 
##  [569] Germany                  Germany                 
##  [571] Germany                  Germany                 
##  [573] Germany                  Germany                 
##  [575] Germany                  Germany                 
##  [577] Ghana                    Ghana                   
##  [579] Ghana                    Ghana                   
##  [581] Ghana                    Ghana                   
##  [583] Ghana                    Ghana                   
##  [585] Ghana                    Ghana                   
##  [587] Ghana                    Ghana                   
##  [589] Greece                   Greece                  
##  [591] Greece                   Greece                  
##  [593] Greece                   Greece                  
##  [595] Greece                   Greece                  
##  [597] Greece                   Greece                  
##  [599] Greece                   Greece                  
##  [601] Guatemala                Guatemala               
##  [603] Guatemala                Guatemala               
##  [605] Guatemala                Guatemala               
##  [607] Guatemala                Guatemala               
##  [609] Guatemala                Guatemala               
##  [611] Guatemala                Guatemala               
##  [613] Guinea                   Guinea                  
##  [615] Guinea                   Guinea                  
##  [617] Guinea                   Guinea                  
##  [619] Guinea                   Guinea                  
##  [621] Guinea                   Guinea                  
##  [623] Guinea                   Guinea                  
##  [625] Guinea-Bissau            Guinea-Bissau           
##  [627] Guinea-Bissau            Guinea-Bissau           
##  [629] Guinea-Bissau            Guinea-Bissau           
##  [631] Guinea-Bissau            Guinea-Bissau           
##  [633] Guinea-Bissau            Guinea-Bissau           
##  [635] Guinea-Bissau            Guinea-Bissau           
##  [637] Haiti                    Haiti                   
##  [639] Haiti                    Haiti                   
##  [641] Haiti                    Haiti                   
##  [643] Haiti                    Haiti                   
##  [645] Haiti                    Haiti                   
##  [647] Haiti                    Haiti                   
##  [649] Honduras                 Honduras                
##  [651] Honduras                 Honduras                
##  [653] Honduras                 Honduras                
##  [655] Honduras                 Honduras                
##  [657] Honduras                 Honduras                
##  [659] Honduras                 Honduras                
##  [661] Hong Kong, China         Hong Kong, China        
##  [663] Hong Kong, China         Hong Kong, China        
##  [665] Hong Kong, China         Hong Kong, China        
##  [667] Hong Kong, China         Hong Kong, China        
##  [669] Hong Kong, China         Hong Kong, China        
##  [671] Hong Kong, China         Hong Kong, China        
##  [673] Hungary                  Hungary                 
##  [675] Hungary                  Hungary                 
##  [677] Hungary                  Hungary                 
##  [679] Hungary                  Hungary                 
##  [681] Hungary                  Hungary                 
##  [683] Hungary                  Hungary                 
##  [685] Iceland                  Iceland                 
##  [687] Iceland                  Iceland                 
##  [689] Iceland                  Iceland                 
##  [691] Iceland                  Iceland                 
##  [693] Iceland                  Iceland                 
##  [695] Iceland                  Iceland                 
##  [697] India                    India                   
##  [699] India                    India                   
##  [701] India                    India                   
##  [703] India                    India                   
##  [705] India                    India                   
##  [707] India                    India                   
##  [709] Indonesia                Indonesia               
##  [711] Indonesia                Indonesia               
##  [713] Indonesia                Indonesia               
##  [715] Indonesia                Indonesia               
##  [717] Indonesia                Indonesia               
##  [719] Indonesia                Indonesia               
##  [721] Iran                     Iran                    
##  [723] Iran                     Iran                    
##  [725] Iran                     Iran                    
##  [727] Iran                     Iran                    
##  [729] Iran                     Iran                    
##  [731] Iran                     Iran                    
##  [733] Iraq                     Iraq                    
##  [735] Iraq                     Iraq                    
##  [737] Iraq                     Iraq                    
##  [739] Iraq                     Iraq                    
##  [741] Iraq                     Iraq                    
##  [743] Iraq                     Iraq                    
##  [745] Ireland                  Ireland                 
##  [747] Ireland                  Ireland                 
##  [749] Ireland                  Ireland                 
##  [751] Ireland                  Ireland                 
##  [753] Ireland                  Ireland                 
##  [755] Ireland                  Ireland                 
##  [757] Israel                   Israel                  
##  [759] Israel                   Israel                  
##  [761] Israel                   Israel                  
##  [763] Israel                   Israel                  
##  [765] Israel                   Israel                  
##  [767] Israel                   Israel                  
##  [769] Italy                    Italy                   
##  [771] Italy                    Italy                   
##  [773] Italy                    Italy                   
##  [775] Italy                    Italy                   
##  [777] Italy                    Italy                   
##  [779] Italy                    Italy                   
##  [781] Jamaica                  Jamaica                 
##  [783] Jamaica                  Jamaica                 
##  [785] Jamaica                  Jamaica                 
##  [787] Jamaica                  Jamaica                 
##  [789] Jamaica                  Jamaica                 
##  [791] Jamaica                  Jamaica                 
##  [793] Japan                    Japan                   
##  [795] Japan                    Japan                   
##  [797] Japan                    Japan                   
##  [799] Japan                    Japan                   
##  [801] Japan                    Japan                   
##  [803] Japan                    Japan                   
##  [805] Jordan                   Jordan                  
##  [807] Jordan                   Jordan                  
##  [809] Jordan                   Jordan                  
##  [811] Jordan                   Jordan                  
##  [813] Jordan                   Jordan                  
##  [815] Jordan                   Jordan                  
##  [817] Kenya                    Kenya                   
##  [819] Kenya                    Kenya                   
##  [821] Kenya                    Kenya                   
##  [823] Kenya                    Kenya                   
##  [825] Kenya                    Kenya                   
##  [827] Kenya                    Kenya                   
##  [829] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [831] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [833] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [835] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [837] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [839] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [841] Korea, Rep.              Korea, Rep.             
##  [843] Korea, Rep.              Korea, Rep.             
##  [845] Korea, Rep.              Korea, Rep.             
##  [847] Korea, Rep.              Korea, Rep.             
##  [849] Korea, Rep.              Korea, Rep.             
##  [851] Korea, Rep.              Korea, Rep.             
##  [853] Kuwait                   Kuwait                  
##  [855] Kuwait                   Kuwait                  
##  [857] Kuwait                   Kuwait                  
##  [859] Kuwait                   Kuwait                  
##  [861] Kuwait                   Kuwait                  
##  [863] Kuwait                   Kuwait                  
##  [865] Lebanon                  Lebanon                 
##  [867] Lebanon                  Lebanon                 
##  [869] Lebanon                  Lebanon                 
##  [871] Lebanon                  Lebanon                 
##  [873] Lebanon                  Lebanon                 
##  [875] Lebanon                  Lebanon                 
##  [877] Lesotho                  Lesotho                 
##  [879] Lesotho                  Lesotho                 
##  [881] Lesotho                  Lesotho                 
##  [883] Lesotho                  Lesotho                 
##  [885] Lesotho                  Lesotho                 
##  [887] Lesotho                  Lesotho                 
##  [889] Liberia                  Liberia                 
##  [891] Liberia                  Liberia                 
##  [893] Liberia                  Liberia                 
##  [895] Liberia                  Liberia                 
##  [897] Liberia                  Liberia                 
##  [899] Liberia                  Liberia                 
##  [901] Libya                    Libya                   
##  [903] Libya                    Libya                   
##  [905] Libya                    Libya                   
##  [907] Libya                    Libya                   
##  [909] Libya                    Libya                   
##  [911] Libya                    Libya                   
##  [913] Madagascar               Madagascar              
##  [915] Madagascar               Madagascar              
##  [917] Madagascar               Madagascar              
##  [919] Madagascar               Madagascar              
##  [921] Madagascar               Madagascar              
##  [923] Madagascar               Madagascar              
##  [925] Malawi                   Malawi                  
##  [927] Malawi                   Malawi                  
##  [929] Malawi                   Malawi                  
##  [931] Malawi                   Malawi                  
##  [933] Malawi                   Malawi                  
##  [935] Malawi                   Malawi                  
##  [937] Malaysia                 Malaysia                
##  [939] Malaysia                 Malaysia                
##  [941] Malaysia                 Malaysia                
##  [943] Malaysia                 Malaysia                
##  [945] Malaysia                 Malaysia                
##  [947] Malaysia                 Malaysia                
##  [949] Mali                     Mali                    
##  [951] Mali                     Mali                    
##  [953] Mali                     Mali                    
##  [955] Mali                     Mali                    
##  [957] Mali                     Mali                    
##  [959] Mali                     Mali                    
##  [961] Mauritania               Mauritania              
##  [963] Mauritania               Mauritania              
##  [965] Mauritania               Mauritania              
##  [967] Mauritania               Mauritania              
##  [969] Mauritania               Mauritania              
##  [971] Mauritania               Mauritania              
##  [973] Mauritius                Mauritius               
##  [975] Mauritius                Mauritius               
##  [977] Mauritius                Mauritius               
##  [979] Mauritius                Mauritius               
##  [981] Mauritius                Mauritius               
##  [983] Mauritius                Mauritius               
##  [985] Mexico                   Mexico                  
##  [987] Mexico                   Mexico                  
##  [989] Mexico                   Mexico                  
##  [991] Mexico                   Mexico                  
##  [993] Mexico                   Mexico                  
##  [995] Mexico                   Mexico                  
##  [997] Mongolia                 Mongolia                
##  [999] Mongolia                 Mongolia                
## [1001] Mongolia                 Mongolia                
## [1003] Mongolia                 Mongolia                
## [1005] Mongolia                 Mongolia                
## [1007] Mongolia                 Mongolia                
## [1009] Montenegro               Montenegro              
## [1011] Montenegro               Montenegro              
## [1013] Montenegro               Montenegro              
## [1015] Montenegro               Montenegro              
## [1017] Montenegro               Montenegro              
## [1019] Montenegro               Montenegro              
## [1021] Morocco                  Morocco                 
## [1023] Morocco                  Morocco                 
## [1025] Morocco                  Morocco                 
## [1027] Morocco                  Morocco                 
## [1029] Morocco                  Morocco                 
## [1031] Morocco                  Morocco                 
## [1033] Mozambique               Mozambique              
## [1035] Mozambique               Mozambique              
## [1037] Mozambique               Mozambique              
## [1039] Mozambique               Mozambique              
## [1041] Mozambique               Mozambique              
## [1043] Mozambique               Mozambique              
## [1045] Myanmar                  Myanmar                 
## [1047] Myanmar                  Myanmar                 
## [1049] Myanmar                  Myanmar                 
## [1051] Myanmar                  Myanmar                 
## [1053] Myanmar                  Myanmar                 
## [1055] Myanmar                  Myanmar                 
## [1057] Namibia                  Namibia                 
## [1059] Namibia                  Namibia                 
## [1061] Namibia                  Namibia                 
## [1063] Namibia                  Namibia                 
## [1065] Namibia                  Namibia                 
## [1067] Namibia                  Namibia                 
## [1069] Nepal                    Nepal                   
## [1071] Nepal                    Nepal                   
## [1073] Nepal                    Nepal                   
## [1075] Nepal                    Nepal                   
## [1077] Nepal                    Nepal                   
## [1079] Nepal                    Nepal                   
## [1081] Netherlands              Netherlands             
## [1083] Netherlands              Netherlands             
## [1085] Netherlands              Netherlands             
## [1087] Netherlands              Netherlands             
## [1089] Netherlands              Netherlands             
## [1091] Netherlands              Netherlands             
## [1093] New Zealand              New Zealand             
## [1095] New Zealand              New Zealand             
## [1097] New Zealand              New Zealand             
## [1099] New Zealand              New Zealand             
## [1101] New Zealand              New Zealand             
## [1103] New Zealand              New Zealand             
## [1105] Nicaragua                Nicaragua               
## [1107] Nicaragua                Nicaragua               
## [1109] Nicaragua                Nicaragua               
## [1111] Nicaragua                Nicaragua               
## [1113] Nicaragua                Nicaragua               
## [1115] Nicaragua                Nicaragua               
## [1117] Niger                    Niger                   
## [1119] Niger                    Niger                   
## [1121] Niger                    Niger                   
## [1123] Niger                    Niger                   
## [1125] Niger                    Niger                   
## [1127] Niger                    Niger                   
## [1129] Nigeria                  Nigeria                 
## [1131] Nigeria                  Nigeria                 
## [1133] Nigeria                  Nigeria                 
## [1135] Nigeria                  Nigeria                 
## [1137] Nigeria                  Nigeria                 
## [1139] Nigeria                  Nigeria                 
## [1141] Norway                   Norway                  
## [1143] Norway                   Norway                  
## [1145] Norway                   Norway                  
## [1147] Norway                   Norway                  
## [1149] Norway                   Norway                  
## [1151] Norway                   Norway                  
## [1153] Oman                     Oman                    
## [1155] Oman                     Oman                    
## [1157] Oman                     Oman                    
## [1159] Oman                     Oman                    
## [1161] Oman                     Oman                    
## [1163] Oman                     Oman                    
## [1165] Pakistan                 Pakistan                
## [1167] Pakistan                 Pakistan                
## [1169] Pakistan                 Pakistan                
## [1171] Pakistan                 Pakistan                
## [1173] Pakistan                 Pakistan                
## [1175] Pakistan                 Pakistan                
## [1177] Panama                   Panama                  
## [1179] Panama                   Panama                  
## [1181] Panama                   Panama                  
## [1183] Panama                   Panama                  
## [1185] Panama                   Panama                  
## [1187] Panama                   Panama                  
## [1189] Paraguay                 Paraguay                
## [1191] Paraguay                 Paraguay                
## [1193] Paraguay                 Paraguay                
## [1195] Paraguay                 Paraguay                
## [1197] Paraguay                 Paraguay                
## [1199] Paraguay                 Paraguay                
## [1201] Peru                     Peru                    
## [1203] Peru                     Peru                    
## [1205] Peru                     Peru                    
## [1207] Peru                     Peru                    
## [1209] Peru                     Peru                    
## [1211] Peru                     Peru                    
## [1213] Philippines              Philippines             
## [1215] Philippines              Philippines             
## [1217] Philippines              Philippines             
## [1219] Philippines              Philippines             
## [1221] Philippines              Philippines             
## [1223] Philippines              Philippines             
## [1225] Poland                   Poland                  
## [1227] Poland                   Poland                  
## [1229] Poland                   Poland                  
## [1231] Poland                   Poland                  
## [1233] Poland                   Poland                  
## [1235] Poland                   Poland                  
## [1237] Portugal                 Portugal                
## [1239] Portugal                 Portugal                
## [1241] Portugal                 Portugal                
## [1243] Portugal                 Portugal                
## [1245] Portugal                 Portugal                
## [1247] Portugal                 Portugal                
## [1249] Puerto Rico              Puerto Rico             
## [1251] Puerto Rico              Puerto Rico             
## [1253] Puerto Rico              Puerto Rico             
## [1255] Puerto Rico              Puerto Rico             
## [1257] Puerto Rico              Puerto Rico             
## [1259] Puerto Rico              Puerto Rico             
## [1261] Reunion                  Reunion                 
## [1263] Reunion                  Reunion                 
## [1265] Reunion                  Reunion                 
## [1267] Reunion                  Reunion                 
## [1269] Reunion                  Reunion                 
## [1271] Reunion                  Reunion                 
## [1273] Romania                  Romania                 
## [1275] Romania                  Romania                 
## [1277] Romania                  Romania                 
## [1279] Romania                  Romania                 
## [1281] Romania                  Romania                 
## [1283] Romania                  Romania                 
## [1285] Rwanda                   Rwanda                  
## [1287] Rwanda                   Rwanda                  
## [1289] Rwanda                   Rwanda                  
## [1291] Rwanda                   Rwanda                  
## [1293] Rwanda                   Rwanda                  
## [1295] Rwanda                   Rwanda                  
## [1297] Sao Tome and Principe    Sao Tome and Principe   
## [1299] Sao Tome and Principe    Sao Tome and Principe   
## [1301] Sao Tome and Principe    Sao Tome and Principe   
## [1303] Sao Tome and Principe    Sao Tome and Principe   
## [1305] Sao Tome and Principe    Sao Tome and Principe   
## [1307] Sao Tome and Principe    Sao Tome and Principe   
## [1309] Saudi Arabia             Saudi Arabia            
## [1311] Saudi Arabia             Saudi Arabia            
## [1313] Saudi Arabia             Saudi Arabia            
## [1315] Saudi Arabia             Saudi Arabia            
## [1317] Saudi Arabia             Saudi Arabia            
## [1319] Saudi Arabia             Saudi Arabia            
## [1321] Senegal                  Senegal                 
## [1323] Senegal                  Senegal                 
## [1325] Senegal                  Senegal                 
## [1327] Senegal                  Senegal                 
## [1329] Senegal                  Senegal                 
## [1331] Senegal                  Senegal                 
## [1333] Serbia                   Serbia                  
## [1335] Serbia                   Serbia                  
## [1337] Serbia                   Serbia                  
## [1339] Serbia                   Serbia                  
## [1341] Serbia                   Serbia                  
## [1343] Serbia                   Serbia                  
## [1345] Sierra Leone             Sierra Leone            
## [1347] Sierra Leone             Sierra Leone            
## [1349] Sierra Leone             Sierra Leone            
## [1351] Sierra Leone             Sierra Leone            
## [1353] Sierra Leone             Sierra Leone            
## [1355] Sierra Leone             Sierra Leone            
## [1357] Singapore                Singapore               
## [1359] Singapore                Singapore               
## [1361] Singapore                Singapore               
## [1363] Singapore                Singapore               
## [1365] Singapore                Singapore               
## [1367] Singapore                Singapore               
## [1369] Slovak Republic          Slovak Republic         
## [1371] Slovak Republic          Slovak Republic         
## [1373] Slovak Republic          Slovak Republic         
## [1375] Slovak Republic          Slovak Republic         
## [1377] Slovak Republic          Slovak Republic         
## [1379] Slovak Republic          Slovak Republic         
## [1381] Slovenia                 Slovenia                
## [1383] Slovenia                 Slovenia                
## [1385] Slovenia                 Slovenia                
## [1387] Slovenia                 Slovenia                
## [1389] Slovenia                 Slovenia                
## [1391] Slovenia                 Slovenia                
## [1393] Somalia                  Somalia                 
## [1395] Somalia                  Somalia                 
## [1397] Somalia                  Somalia                 
## [1399] Somalia                  Somalia                 
## [1401] Somalia                  Somalia                 
## [1403] Somalia                  Somalia                 
## [1405] South Africa             South Africa            
## [1407] South Africa             South Africa            
## [1409] South Africa             South Africa            
## [1411] South Africa             South Africa            
## [1413] South Africa             South Africa            
## [1415] South Africa             South Africa            
## [1417] Spain                    Spain                   
## [1419] Spain                    Spain                   
## [1421] Spain                    Spain                   
## [1423] Spain                    Spain                   
## [1425] Spain                    Spain                   
## [1427] Spain                    Spain                   
## [1429] Sri Lanka                Sri Lanka               
## [1431] Sri Lanka                Sri Lanka               
## [1433] Sri Lanka                Sri Lanka               
## [1435] Sri Lanka                Sri Lanka               
## [1437] Sri Lanka                Sri Lanka               
## [1439] Sri Lanka                Sri Lanka               
## [1441] Sudan                    Sudan                   
## [1443] Sudan                    Sudan                   
## [1445] Sudan                    Sudan                   
## [1447] Sudan                    Sudan                   
## [1449] Sudan                    Sudan                   
## [1451] Sudan                    Sudan                   
## [1453] Swaziland                Swaziland               
## [1455] Swaziland                Swaziland               
## [1457] Swaziland                Swaziland               
## [1459] Swaziland                Swaziland               
## [1461] Swaziland                Swaziland               
## [1463] Swaziland                Swaziland               
## [1465] Sweden                   Sweden                  
## [1467] Sweden                   Sweden                  
## [1469] Sweden                   Sweden                  
## [1471] Sweden                   Sweden                  
## [1473] Sweden                   Sweden                  
## [1475] Sweden                   Sweden                  
## [1477] Switzerland              Switzerland             
## [1479] Switzerland              Switzerland             
## [1481] Switzerland              Switzerland             
## [1483] Switzerland              Switzerland             
## [1485] Switzerland              Switzerland             
## [1487] Switzerland              Switzerland             
## [1489] Syria                    Syria                   
## [1491] Syria                    Syria                   
## [1493] Syria                    Syria                   
## [1495] Syria                    Syria                   
## [1497] Syria                    Syria                   
## [1499] Syria                    Syria                   
## [1501] Taiwan                   Taiwan                  
## [1503] Taiwan                   Taiwan                  
## [1505] Taiwan                   Taiwan                  
## [1507] Taiwan                   Taiwan                  
## [1509] Taiwan                   Taiwan                  
## [1511] Taiwan                   Taiwan                  
## [1513] Tanzania                 Tanzania                
## [1515] Tanzania                 Tanzania                
## [1517] Tanzania                 Tanzania                
## [1519] Tanzania                 Tanzania                
## [1521] Tanzania                 Tanzania                
## [1523] Tanzania                 Tanzania                
## [1525] Thailand                 Thailand                
## [1527] Thailand                 Thailand                
## [1529] Thailand                 Thailand                
## [1531] Thailand                 Thailand                
## [1533] Thailand                 Thailand                
## [1535] Thailand                 Thailand                
## [1537] Togo                     Togo                    
## [1539] Togo                     Togo                    
## [1541] Togo                     Togo                    
## [1543] Togo                     Togo                    
## [1545] Togo                     Togo                    
## [1547] Togo                     Togo                    
## [1549] Trinidad and Tobago      Trinidad and Tobago     
## [1551] Trinidad and Tobago      Trinidad and Tobago     
## [1553] Trinidad and Tobago      Trinidad and Tobago     
## [1555] Trinidad and Tobago      Trinidad and Tobago     
## [1557] Trinidad and Tobago      Trinidad and Tobago     
## [1559] Trinidad and Tobago      Trinidad and Tobago     
## [1561] Tunisia                  Tunisia                 
## [1563] Tunisia                  Tunisia                 
## [1565] Tunisia                  Tunisia                 
## [1567] Tunisia                  Tunisia                 
## [1569] Tunisia                  Tunisia                 
## [1571] Tunisia                  Tunisia                 
## [1573] Turkey                   Turkey                  
## [1575] Turkey                   Turkey                  
## [1577] Turkey                   Turkey                  
## [1579] Turkey                   Turkey                  
## [1581] Turkey                   Turkey                  
## [1583] Turkey                   Turkey                  
## [1585] Uganda                   Uganda                  
## [1587] Uganda                   Uganda                  
## [1589] Uganda                   Uganda                  
## [1591] Uganda                   Uganda                  
## [1593] Uganda                   Uganda                  
## [1595] Uganda                   Uganda                  
## [1597] United Kingdom           United Kingdom          
## [1599] United Kingdom           United Kingdom          
## [1601] United Kingdom           United Kingdom          
## [1603] United Kingdom           United Kingdom          
## [1605] United Kingdom           United Kingdom          
## [1607] United Kingdom           United Kingdom          
## [1609] United States            United States           
## [1611] United States            United States           
## [1613] United States            United States           
## [1615] United States            United States           
## [1617] United States            United States           
## [1619] United States            United States           
## [1621] Uruguay                  Uruguay                 
## [1623] Uruguay                  Uruguay                 
## [1625] Uruguay                  Uruguay                 
## [1627] Uruguay                  Uruguay                 
## [1629] Uruguay                  Uruguay                 
## [1631] Uruguay                  Uruguay                 
## [1633] Venezuela                Venezuela               
## [1635] Venezuela                Venezuela               
## [1637] Venezuela                Venezuela               
## [1639] Venezuela                Venezuela               
## [1641] Venezuela                Venezuela               
## [1643] Venezuela                Venezuela               
## [1645] Vietnam                  Vietnam                 
## [1647] Vietnam                  Vietnam                 
## [1649] Vietnam                  Vietnam                 
## [1651] Vietnam                  Vietnam                 
## [1653] Vietnam                  Vietnam                 
## [1655] Vietnam                  Vietnam                 
## [1657] West Bank and Gaza       West Bank and Gaza      
## [1659] West Bank and Gaza       West Bank and Gaza      
## [1661] West Bank and Gaza       West Bank and Gaza      
## [1663] West Bank and Gaza       West Bank and Gaza      
## [1665] West Bank and Gaza       West Bank and Gaza      
## [1667] West Bank and Gaza       West Bank and Gaza      
## [1669] Yemen, Rep.              Yemen, Rep.             
## [1671] Yemen, Rep.              Yemen, Rep.             
## [1673] Yemen, Rep.              Yemen, Rep.             
## [1675] Yemen, Rep.              Yemen, Rep.             
## [1677] Yemen, Rep.              Yemen, Rep.             
## [1679] Yemen, Rep.              Yemen, Rep.             
## [1681] Zambia                   Zambia                  
## [1683] Zambia                   Zambia                  
## [1685] Zambia                   Zambia                  
## [1687] Zambia                   Zambia                  
## [1689] Zambia                   Zambia                  
## [1691] Zambia                   Zambia                  
## [1693] Zimbabwe                 Zimbabwe                
## [1695] Zimbabwe                 Zimbabwe                
## [1697] Zimbabwe                 Zimbabwe                
## [1699] Zimbabwe                 Zimbabwe                
## [1701] Zimbabwe                 Zimbabwe                
## [1703] Zimbabwe                 Zimbabwe                
## 142 Levels: Afghanistan Albania Algeria Angola Argentina ... Zimbabwe
```

---
## data.frame - indexing

- `$` operator can be used to retrieve a variable (column) by its name
- The result is a vector


```r
countries &lt;- gapminder$country
countries
```

```
##    [1] Afghanistan              Afghanistan             
##    [3] Afghanistan              Afghanistan             
##    [5] Afghanistan              Afghanistan             
##    [7] Afghanistan              Afghanistan             
##    [9] Afghanistan              Afghanistan             
##   [11] Afghanistan              Afghanistan             
##   [13] Albania                  Albania                 
##   [15] Albania                  Albania                 
##   [17] Albania                  Albania                 
##   [19] Albania                  Albania                 
##   [21] Albania                  Albania                 
##   [23] Albania                  Albania                 
##   [25] Algeria                  Algeria                 
##   [27] Algeria                  Algeria                 
##   [29] Algeria                  Algeria                 
##   [31] Algeria                  Algeria                 
##   [33] Algeria                  Algeria                 
##   [35] Algeria                  Algeria                 
##   [37] Angola                   Angola                  
##   [39] Angola                   Angola                  
##   [41] Angola                   Angola                  
##   [43] Angola                   Angola                  
##   [45] Angola                   Angola                  
##   [47] Angola                   Angola                  
##   [49] Argentina                Argentina               
##   [51] Argentina                Argentina               
##   [53] Argentina                Argentina               
##   [55] Argentina                Argentina               
##   [57] Argentina                Argentina               
##   [59] Argentina                Argentina               
##   [61] Australia                Australia               
##   [63] Australia                Australia               
##   [65] Australia                Australia               
##   [67] Australia                Australia               
##   [69] Australia                Australia               
##   [71] Australia                Australia               
##   [73] Austria                  Austria                 
##   [75] Austria                  Austria                 
##   [77] Austria                  Austria                 
##   [79] Austria                  Austria                 
##   [81] Austria                  Austria                 
##   [83] Austria                  Austria                 
##   [85] Bahrain                  Bahrain                 
##   [87] Bahrain                  Bahrain                 
##   [89] Bahrain                  Bahrain                 
##   [91] Bahrain                  Bahrain                 
##   [93] Bahrain                  Bahrain                 
##   [95] Bahrain                  Bahrain                 
##   [97] Bangladesh               Bangladesh              
##   [99] Bangladesh               Bangladesh              
##  [101] Bangladesh               Bangladesh              
##  [103] Bangladesh               Bangladesh              
##  [105] Bangladesh               Bangladesh              
##  [107] Bangladesh               Bangladesh              
##  [109] Belgium                  Belgium                 
##  [111] Belgium                  Belgium                 
##  [113] Belgium                  Belgium                 
##  [115] Belgium                  Belgium                 
##  [117] Belgium                  Belgium                 
##  [119] Belgium                  Belgium                 
##  [121] Benin                    Benin                   
##  [123] Benin                    Benin                   
##  [125] Benin                    Benin                   
##  [127] Benin                    Benin                   
##  [129] Benin                    Benin                   
##  [131] Benin                    Benin                   
##  [133] Bolivia                  Bolivia                 
##  [135] Bolivia                  Bolivia                 
##  [137] Bolivia                  Bolivia                 
##  [139] Bolivia                  Bolivia                 
##  [141] Bolivia                  Bolivia                 
##  [143] Bolivia                  Bolivia                 
##  [145] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [147] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [149] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [151] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [153] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [155] Bosnia and Herzegovina   Bosnia and Herzegovina  
##  [157] Botswana                 Botswana                
##  [159] Botswana                 Botswana                
##  [161] Botswana                 Botswana                
##  [163] Botswana                 Botswana                
##  [165] Botswana                 Botswana                
##  [167] Botswana                 Botswana                
##  [169] Brazil                   Brazil                  
##  [171] Brazil                   Brazil                  
##  [173] Brazil                   Brazil                  
##  [175] Brazil                   Brazil                  
##  [177] Brazil                   Brazil                  
##  [179] Brazil                   Brazil                  
##  [181] Bulgaria                 Bulgaria                
##  [183] Bulgaria                 Bulgaria                
##  [185] Bulgaria                 Bulgaria                
##  [187] Bulgaria                 Bulgaria                
##  [189] Bulgaria                 Bulgaria                
##  [191] Bulgaria                 Bulgaria                
##  [193] Burkina Faso             Burkina Faso            
##  [195] Burkina Faso             Burkina Faso            
##  [197] Burkina Faso             Burkina Faso            
##  [199] Burkina Faso             Burkina Faso            
##  [201] Burkina Faso             Burkina Faso            
##  [203] Burkina Faso             Burkina Faso            
##  [205] Burundi                  Burundi                 
##  [207] Burundi                  Burundi                 
##  [209] Burundi                  Burundi                 
##  [211] Burundi                  Burundi                 
##  [213] Burundi                  Burundi                 
##  [215] Burundi                  Burundi                 
##  [217] Cambodia                 Cambodia                
##  [219] Cambodia                 Cambodia                
##  [221] Cambodia                 Cambodia                
##  [223] Cambodia                 Cambodia                
##  [225] Cambodia                 Cambodia                
##  [227] Cambodia                 Cambodia                
##  [229] Cameroon                 Cameroon                
##  [231] Cameroon                 Cameroon                
##  [233] Cameroon                 Cameroon                
##  [235] Cameroon                 Cameroon                
##  [237] Cameroon                 Cameroon                
##  [239] Cameroon                 Cameroon                
##  [241] Canada                   Canada                  
##  [243] Canada                   Canada                  
##  [245] Canada                   Canada                  
##  [247] Canada                   Canada                  
##  [249] Canada                   Canada                  
##  [251] Canada                   Canada                  
##  [253] Central African Republic Central African Republic
##  [255] Central African Republic Central African Republic
##  [257] Central African Republic Central African Republic
##  [259] Central African Republic Central African Republic
##  [261] Central African Republic Central African Republic
##  [263] Central African Republic Central African Republic
##  [265] Chad                     Chad                    
##  [267] Chad                     Chad                    
##  [269] Chad                     Chad                    
##  [271] Chad                     Chad                    
##  [273] Chad                     Chad                    
##  [275] Chad                     Chad                    
##  [277] Chile                    Chile                   
##  [279] Chile                    Chile                   
##  [281] Chile                    Chile                   
##  [283] Chile                    Chile                   
##  [285] Chile                    Chile                   
##  [287] Chile                    Chile                   
##  [289] China                    China                   
##  [291] China                    China                   
##  [293] China                    China                   
##  [295] China                    China                   
##  [297] China                    China                   
##  [299] China                    China                   
##  [301] Colombia                 Colombia                
##  [303] Colombia                 Colombia                
##  [305] Colombia                 Colombia                
##  [307] Colombia                 Colombia                
##  [309] Colombia                 Colombia                
##  [311] Colombia                 Colombia                
##  [313] Comoros                  Comoros                 
##  [315] Comoros                  Comoros                 
##  [317] Comoros                  Comoros                 
##  [319] Comoros                  Comoros                 
##  [321] Comoros                  Comoros                 
##  [323] Comoros                  Comoros                 
##  [325] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [327] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [329] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [331] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [333] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [335] Congo, Dem. Rep.         Congo, Dem. Rep.        
##  [337] Congo, Rep.              Congo, Rep.             
##  [339] Congo, Rep.              Congo, Rep.             
##  [341] Congo, Rep.              Congo, Rep.             
##  [343] Congo, Rep.              Congo, Rep.             
##  [345] Congo, Rep.              Congo, Rep.             
##  [347] Congo, Rep.              Congo, Rep.             
##  [349] Costa Rica               Costa Rica              
##  [351] Costa Rica               Costa Rica              
##  [353] Costa Rica               Costa Rica              
##  [355] Costa Rica               Costa Rica              
##  [357] Costa Rica               Costa Rica              
##  [359] Costa Rica               Costa Rica              
##  [361] Cote d'Ivoire            Cote d'Ivoire           
##  [363] Cote d'Ivoire            Cote d'Ivoire           
##  [365] Cote d'Ivoire            Cote d'Ivoire           
##  [367] Cote d'Ivoire            Cote d'Ivoire           
##  [369] Cote d'Ivoire            Cote d'Ivoire           
##  [371] Cote d'Ivoire            Cote d'Ivoire           
##  [373] Croatia                  Croatia                 
##  [375] Croatia                  Croatia                 
##  [377] Croatia                  Croatia                 
##  [379] Croatia                  Croatia                 
##  [381] Croatia                  Croatia                 
##  [383] Croatia                  Croatia                 
##  [385] Cuba                     Cuba                    
##  [387] Cuba                     Cuba                    
##  [389] Cuba                     Cuba                    
##  [391] Cuba                     Cuba                    
##  [393] Cuba                     Cuba                    
##  [395] Cuba                     Cuba                    
##  [397] Czech Republic           Czech Republic          
##  [399] Czech Republic           Czech Republic          
##  [401] Czech Republic           Czech Republic          
##  [403] Czech Republic           Czech Republic          
##  [405] Czech Republic           Czech Republic          
##  [407] Czech Republic           Czech Republic          
##  [409] Denmark                  Denmark                 
##  [411] Denmark                  Denmark                 
##  [413] Denmark                  Denmark                 
##  [415] Denmark                  Denmark                 
##  [417] Denmark                  Denmark                 
##  [419] Denmark                  Denmark                 
##  [421] Djibouti                 Djibouti                
##  [423] Djibouti                 Djibouti                
##  [425] Djibouti                 Djibouti                
##  [427] Djibouti                 Djibouti                
##  [429] Djibouti                 Djibouti                
##  [431] Djibouti                 Djibouti                
##  [433] Dominican Republic       Dominican Republic      
##  [435] Dominican Republic       Dominican Republic      
##  [437] Dominican Republic       Dominican Republic      
##  [439] Dominican Republic       Dominican Republic      
##  [441] Dominican Republic       Dominican Republic      
##  [443] Dominican Republic       Dominican Republic      
##  [445] Ecuador                  Ecuador                 
##  [447] Ecuador                  Ecuador                 
##  [449] Ecuador                  Ecuador                 
##  [451] Ecuador                  Ecuador                 
##  [453] Ecuador                  Ecuador                 
##  [455] Ecuador                  Ecuador                 
##  [457] Egypt                    Egypt                   
##  [459] Egypt                    Egypt                   
##  [461] Egypt                    Egypt                   
##  [463] Egypt                    Egypt                   
##  [465] Egypt                    Egypt                   
##  [467] Egypt                    Egypt                   
##  [469] El Salvador              El Salvador             
##  [471] El Salvador              El Salvador             
##  [473] El Salvador              El Salvador             
##  [475] El Salvador              El Salvador             
##  [477] El Salvador              El Salvador             
##  [479] El Salvador              El Salvador             
##  [481] Equatorial Guinea        Equatorial Guinea       
##  [483] Equatorial Guinea        Equatorial Guinea       
##  [485] Equatorial Guinea        Equatorial Guinea       
##  [487] Equatorial Guinea        Equatorial Guinea       
##  [489] Equatorial Guinea        Equatorial Guinea       
##  [491] Equatorial Guinea        Equatorial Guinea       
##  [493] Eritrea                  Eritrea                 
##  [495] Eritrea                  Eritrea                 
##  [497] Eritrea                  Eritrea                 
##  [499] Eritrea                  Eritrea                 
##  [501] Eritrea                  Eritrea                 
##  [503] Eritrea                  Eritrea                 
##  [505] Ethiopia                 Ethiopia                
##  [507] Ethiopia                 Ethiopia                
##  [509] Ethiopia                 Ethiopia                
##  [511] Ethiopia                 Ethiopia                
##  [513] Ethiopia                 Ethiopia                
##  [515] Ethiopia                 Ethiopia                
##  [517] Finland                  Finland                 
##  [519] Finland                  Finland                 
##  [521] Finland                  Finland                 
##  [523] Finland                  Finland                 
##  [525] Finland                  Finland                 
##  [527] Finland                  Finland                 
##  [529] France                   France                  
##  [531] France                   France                  
##  [533] France                   France                  
##  [535] France                   France                  
##  [537] France                   France                  
##  [539] France                   France                  
##  [541] Gabon                    Gabon                   
##  [543] Gabon                    Gabon                   
##  [545] Gabon                    Gabon                   
##  [547] Gabon                    Gabon                   
##  [549] Gabon                    Gabon                   
##  [551] Gabon                    Gabon                   
##  [553] Gambia                   Gambia                  
##  [555] Gambia                   Gambia                  
##  [557] Gambia                   Gambia                  
##  [559] Gambia                   Gambia                  
##  [561] Gambia                   Gambia                  
##  [563] Gambia                   Gambia                  
##  [565] Germany                  Germany                 
##  [567] Germany                  Germany                 
##  [569] Germany                  Germany                 
##  [571] Germany                  Germany                 
##  [573] Germany                  Germany                 
##  [575] Germany                  Germany                 
##  [577] Ghana                    Ghana                   
##  [579] Ghana                    Ghana                   
##  [581] Ghana                    Ghana                   
##  [583] Ghana                    Ghana                   
##  [585] Ghana                    Ghana                   
##  [587] Ghana                    Ghana                   
##  [589] Greece                   Greece                  
##  [591] Greece                   Greece                  
##  [593] Greece                   Greece                  
##  [595] Greece                   Greece                  
##  [597] Greece                   Greece                  
##  [599] Greece                   Greece                  
##  [601] Guatemala                Guatemala               
##  [603] Guatemala                Guatemala               
##  [605] Guatemala                Guatemala               
##  [607] Guatemala                Guatemala               
##  [609] Guatemala                Guatemala               
##  [611] Guatemala                Guatemala               
##  [613] Guinea                   Guinea                  
##  [615] Guinea                   Guinea                  
##  [617] Guinea                   Guinea                  
##  [619] Guinea                   Guinea                  
##  [621] Guinea                   Guinea                  
##  [623] Guinea                   Guinea                  
##  [625] Guinea-Bissau            Guinea-Bissau           
##  [627] Guinea-Bissau            Guinea-Bissau           
##  [629] Guinea-Bissau            Guinea-Bissau           
##  [631] Guinea-Bissau            Guinea-Bissau           
##  [633] Guinea-Bissau            Guinea-Bissau           
##  [635] Guinea-Bissau            Guinea-Bissau           
##  [637] Haiti                    Haiti                   
##  [639] Haiti                    Haiti                   
##  [641] Haiti                    Haiti                   
##  [643] Haiti                    Haiti                   
##  [645] Haiti                    Haiti                   
##  [647] Haiti                    Haiti                   
##  [649] Honduras                 Honduras                
##  [651] Honduras                 Honduras                
##  [653] Honduras                 Honduras                
##  [655] Honduras                 Honduras                
##  [657] Honduras                 Honduras                
##  [659] Honduras                 Honduras                
##  [661] Hong Kong, China         Hong Kong, China        
##  [663] Hong Kong, China         Hong Kong, China        
##  [665] Hong Kong, China         Hong Kong, China        
##  [667] Hong Kong, China         Hong Kong, China        
##  [669] Hong Kong, China         Hong Kong, China        
##  [671] Hong Kong, China         Hong Kong, China        
##  [673] Hungary                  Hungary                 
##  [675] Hungary                  Hungary                 
##  [677] Hungary                  Hungary                 
##  [679] Hungary                  Hungary                 
##  [681] Hungary                  Hungary                 
##  [683] Hungary                  Hungary                 
##  [685] Iceland                  Iceland                 
##  [687] Iceland                  Iceland                 
##  [689] Iceland                  Iceland                 
##  [691] Iceland                  Iceland                 
##  [693] Iceland                  Iceland                 
##  [695] Iceland                  Iceland                 
##  [697] India                    India                   
##  [699] India                    India                   
##  [701] India                    India                   
##  [703] India                    India                   
##  [705] India                    India                   
##  [707] India                    India                   
##  [709] Indonesia                Indonesia               
##  [711] Indonesia                Indonesia               
##  [713] Indonesia                Indonesia               
##  [715] Indonesia                Indonesia               
##  [717] Indonesia                Indonesia               
##  [719] Indonesia                Indonesia               
##  [721] Iran                     Iran                    
##  [723] Iran                     Iran                    
##  [725] Iran                     Iran                    
##  [727] Iran                     Iran                    
##  [729] Iran                     Iran                    
##  [731] Iran                     Iran                    
##  [733] Iraq                     Iraq                    
##  [735] Iraq                     Iraq                    
##  [737] Iraq                     Iraq                    
##  [739] Iraq                     Iraq                    
##  [741] Iraq                     Iraq                    
##  [743] Iraq                     Iraq                    
##  [745] Ireland                  Ireland                 
##  [747] Ireland                  Ireland                 
##  [749] Ireland                  Ireland                 
##  [751] Ireland                  Ireland                 
##  [753] Ireland                  Ireland                 
##  [755] Ireland                  Ireland                 
##  [757] Israel                   Israel                  
##  [759] Israel                   Israel                  
##  [761] Israel                   Israel                  
##  [763] Israel                   Israel                  
##  [765] Israel                   Israel                  
##  [767] Israel                   Israel                  
##  [769] Italy                    Italy                   
##  [771] Italy                    Italy                   
##  [773] Italy                    Italy                   
##  [775] Italy                    Italy                   
##  [777] Italy                    Italy                   
##  [779] Italy                    Italy                   
##  [781] Jamaica                  Jamaica                 
##  [783] Jamaica                  Jamaica                 
##  [785] Jamaica                  Jamaica                 
##  [787] Jamaica                  Jamaica                 
##  [789] Jamaica                  Jamaica                 
##  [791] Jamaica                  Jamaica                 
##  [793] Japan                    Japan                   
##  [795] Japan                    Japan                   
##  [797] Japan                    Japan                   
##  [799] Japan                    Japan                   
##  [801] Japan                    Japan                   
##  [803] Japan                    Japan                   
##  [805] Jordan                   Jordan                  
##  [807] Jordan                   Jordan                  
##  [809] Jordan                   Jordan                  
##  [811] Jordan                   Jordan                  
##  [813] Jordan                   Jordan                  
##  [815] Jordan                   Jordan                  
##  [817] Kenya                    Kenya                   
##  [819] Kenya                    Kenya                   
##  [821] Kenya                    Kenya                   
##  [823] Kenya                    Kenya                   
##  [825] Kenya                    Kenya                   
##  [827] Kenya                    Kenya                   
##  [829] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [831] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [833] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [835] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [837] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [839] Korea, Dem. Rep.         Korea, Dem. Rep.        
##  [841] Korea, Rep.              Korea, Rep.             
##  [843] Korea, Rep.              Korea, Rep.             
##  [845] Korea, Rep.              Korea, Rep.             
##  [847] Korea, Rep.              Korea, Rep.             
##  [849] Korea, Rep.              Korea, Rep.             
##  [851] Korea, Rep.              Korea, Rep.             
##  [853] Kuwait                   Kuwait                  
##  [855] Kuwait                   Kuwait                  
##  [857] Kuwait                   Kuwait                  
##  [859] Kuwait                   Kuwait                  
##  [861] Kuwait                   Kuwait                  
##  [863] Kuwait                   Kuwait                  
##  [865] Lebanon                  Lebanon                 
##  [867] Lebanon                  Lebanon                 
##  [869] Lebanon                  Lebanon                 
##  [871] Lebanon                  Lebanon                 
##  [873] Lebanon                  Lebanon                 
##  [875] Lebanon                  Lebanon                 
##  [877] Lesotho                  Lesotho                 
##  [879] Lesotho                  Lesotho                 
##  [881] Lesotho                  Lesotho                 
##  [883] Lesotho                  Lesotho                 
##  [885] Lesotho                  Lesotho                 
##  [887] Lesotho                  Lesotho                 
##  [889] Liberia                  Liberia                 
##  [891] Liberia                  Liberia                 
##  [893] Liberia                  Liberia                 
##  [895] Liberia                  Liberia                 
##  [897] Liberia                  Liberia                 
##  [899] Liberia                  Liberia                 
##  [901] Libya                    Libya                   
##  [903] Libya                    Libya                   
##  [905] Libya                    Libya                   
##  [907] Libya                    Libya                   
##  [909] Libya                    Libya                   
##  [911] Libya                    Libya                   
##  [913] Madagascar               Madagascar              
##  [915] Madagascar               Madagascar              
##  [917] Madagascar               Madagascar              
##  [919] Madagascar               Madagascar              
##  [921] Madagascar               Madagascar              
##  [923] Madagascar               Madagascar              
##  [925] Malawi                   Malawi                  
##  [927] Malawi                   Malawi                  
##  [929] Malawi                   Malawi                  
##  [931] Malawi                   Malawi                  
##  [933] Malawi                   Malawi                  
##  [935] Malawi                   Malawi                  
##  [937] Malaysia                 Malaysia                
##  [939] Malaysia                 Malaysia                
##  [941] Malaysia                 Malaysia                
##  [943] Malaysia                 Malaysia                
##  [945] Malaysia                 Malaysia                
##  [947] Malaysia                 Malaysia                
##  [949] Mali                     Mali                    
##  [951] Mali                     Mali                    
##  [953] Mali                     Mali                    
##  [955] Mali                     Mali                    
##  [957] Mali                     Mali                    
##  [959] Mali                     Mali                    
##  [961] Mauritania               Mauritania              
##  [963] Mauritania               Mauritania              
##  [965] Mauritania               Mauritania              
##  [967] Mauritania               Mauritania              
##  [969] Mauritania               Mauritania              
##  [971] Mauritania               Mauritania              
##  [973] Mauritius                Mauritius               
##  [975] Mauritius                Mauritius               
##  [977] Mauritius                Mauritius               
##  [979] Mauritius                Mauritius               
##  [981] Mauritius                Mauritius               
##  [983] Mauritius                Mauritius               
##  [985] Mexico                   Mexico                  
##  [987] Mexico                   Mexico                  
##  [989] Mexico                   Mexico                  
##  [991] Mexico                   Mexico                  
##  [993] Mexico                   Mexico                  
##  [995] Mexico                   Mexico                  
##  [997] Mongolia                 Mongolia                
##  [999] Mongolia                 Mongolia                
## [1001] Mongolia                 Mongolia                
## [1003] Mongolia                 Mongolia                
## [1005] Mongolia                 Mongolia                
## [1007] Mongolia                 Mongolia                
## [1009] Montenegro               Montenegro              
## [1011] Montenegro               Montenegro              
## [1013] Montenegro               Montenegro              
## [1015] Montenegro               Montenegro              
## [1017] Montenegro               Montenegro              
## [1019] Montenegro               Montenegro              
## [1021] Morocco                  Morocco                 
## [1023] Morocco                  Morocco                 
## [1025] Morocco                  Morocco                 
## [1027] Morocco                  Morocco                 
## [1029] Morocco                  Morocco                 
## [1031] Morocco                  Morocco                 
## [1033] Mozambique               Mozambique              
## [1035] Mozambique               Mozambique              
## [1037] Mozambique               Mozambique              
## [1039] Mozambique               Mozambique              
## [1041] Mozambique               Mozambique              
## [1043] Mozambique               Mozambique              
## [1045] Myanmar                  Myanmar                 
## [1047] Myanmar                  Myanmar                 
## [1049] Myanmar                  Myanmar                 
## [1051] Myanmar                  Myanmar                 
## [1053] Myanmar                  Myanmar                 
## [1055] Myanmar                  Myanmar                 
## [1057] Namibia                  Namibia                 
## [1059] Namibia                  Namibia                 
## [1061] Namibia                  Namibia                 
## [1063] Namibia                  Namibia                 
## [1065] Namibia                  Namibia                 
## [1067] Namibia                  Namibia                 
## [1069] Nepal                    Nepal                   
## [1071] Nepal                    Nepal                   
## [1073] Nepal                    Nepal                   
## [1075] Nepal                    Nepal                   
## [1077] Nepal                    Nepal                   
## [1079] Nepal                    Nepal                   
## [1081] Netherlands              Netherlands             
## [1083] Netherlands              Netherlands             
## [1085] Netherlands              Netherlands             
## [1087] Netherlands              Netherlands             
## [1089] Netherlands              Netherlands             
## [1091] Netherlands              Netherlands             
## [1093] New Zealand              New Zealand             
## [1095] New Zealand              New Zealand             
## [1097] New Zealand              New Zealand             
## [1099] New Zealand              New Zealand             
## [1101] New Zealand              New Zealand             
## [1103] New Zealand              New Zealand             
## [1105] Nicaragua                Nicaragua               
## [1107] Nicaragua                Nicaragua               
## [1109] Nicaragua                Nicaragua               
## [1111] Nicaragua                Nicaragua               
## [1113] Nicaragua                Nicaragua               
## [1115] Nicaragua                Nicaragua               
## [1117] Niger                    Niger                   
## [1119] Niger                    Niger                   
## [1121] Niger                    Niger                   
## [1123] Niger                    Niger                   
## [1125] Niger                    Niger                   
## [1127] Niger                    Niger                   
## [1129] Nigeria                  Nigeria                 
## [1131] Nigeria                  Nigeria                 
## [1133] Nigeria                  Nigeria                 
## [1135] Nigeria                  Nigeria                 
## [1137] Nigeria                  Nigeria                 
## [1139] Nigeria                  Nigeria                 
## [1141] Norway                   Norway                  
## [1143] Norway                   Norway                  
## [1145] Norway                   Norway                  
## [1147] Norway                   Norway                  
## [1149] Norway                   Norway                  
## [1151] Norway                   Norway                  
## [1153] Oman                     Oman                    
## [1155] Oman                     Oman                    
## [1157] Oman                     Oman                    
## [1159] Oman                     Oman                    
## [1161] Oman                     Oman                    
## [1163] Oman                     Oman                    
## [1165] Pakistan                 Pakistan                
## [1167] Pakistan                 Pakistan                
## [1169] Pakistan                 Pakistan                
## [1171] Pakistan                 Pakistan                
## [1173] Pakistan                 Pakistan                
## [1175] Pakistan                 Pakistan                
## [1177] Panama                   Panama                  
## [1179] Panama                   Panama                  
## [1181] Panama                   Panama                  
## [1183] Panama                   Panama                  
## [1185] Panama                   Panama                  
## [1187] Panama                   Panama                  
## [1189] Paraguay                 Paraguay                
## [1191] Paraguay                 Paraguay                
## [1193] Paraguay                 Paraguay                
## [1195] Paraguay                 Paraguay                
## [1197] Paraguay                 Paraguay                
## [1199] Paraguay                 Paraguay                
## [1201] Peru                     Peru                    
## [1203] Peru                     Peru                    
## [1205] Peru                     Peru                    
## [1207] Peru                     Peru                    
## [1209] Peru                     Peru                    
## [1211] Peru                     Peru                    
## [1213] Philippines              Philippines             
## [1215] Philippines              Philippines             
## [1217] Philippines              Philippines             
## [1219] Philippines              Philippines             
## [1221] Philippines              Philippines             
## [1223] Philippines              Philippines             
## [1225] Poland                   Poland                  
## [1227] Poland                   Poland                  
## [1229] Poland                   Poland                  
## [1231] Poland                   Poland                  
## [1233] Poland                   Poland                  
## [1235] Poland                   Poland                  
## [1237] Portugal                 Portugal                
## [1239] Portugal                 Portugal                
## [1241] Portugal                 Portugal                
## [1243] Portugal                 Portugal                
## [1245] Portugal                 Portugal                
## [1247] Portugal                 Portugal                
## [1249] Puerto Rico              Puerto Rico             
## [1251] Puerto Rico              Puerto Rico             
## [1253] Puerto Rico              Puerto Rico             
## [1255] Puerto Rico              Puerto Rico             
## [1257] Puerto Rico              Puerto Rico             
## [1259] Puerto Rico              Puerto Rico             
## [1261] Reunion                  Reunion                 
## [1263] Reunion                  Reunion                 
## [1265] Reunion                  Reunion                 
## [1267] Reunion                  Reunion                 
## [1269] Reunion                  Reunion                 
## [1271] Reunion                  Reunion                 
## [1273] Romania                  Romania                 
## [1275] Romania                  Romania                 
## [1277] Romania                  Romania                 
## [1279] Romania                  Romania                 
## [1281] Romania                  Romania                 
## [1283] Romania                  Romania                 
## [1285] Rwanda                   Rwanda                  
## [1287] Rwanda                   Rwanda                  
## [1289] Rwanda                   Rwanda                  
## [1291] Rwanda                   Rwanda                  
## [1293] Rwanda                   Rwanda                  
## [1295] Rwanda                   Rwanda                  
## [1297] Sao Tome and Principe    Sao Tome and Principe   
## [1299] Sao Tome and Principe    Sao Tome and Principe   
## [1301] Sao Tome and Principe    Sao Tome and Principe   
## [1303] Sao Tome and Principe    Sao Tome and Principe   
## [1305] Sao Tome and Principe    Sao Tome and Principe   
## [1307] Sao Tome and Principe    Sao Tome and Principe   
## [1309] Saudi Arabia             Saudi Arabia            
## [1311] Saudi Arabia             Saudi Arabia            
## [1313] Saudi Arabia             Saudi Arabia            
## [1315] Saudi Arabia             Saudi Arabia            
## [1317] Saudi Arabia             Saudi Arabia            
## [1319] Saudi Arabia             Saudi Arabia            
## [1321] Senegal                  Senegal                 
## [1323] Senegal                  Senegal                 
## [1325] Senegal                  Senegal                 
## [1327] Senegal                  Senegal                 
## [1329] Senegal                  Senegal                 
## [1331] Senegal                  Senegal                 
## [1333] Serbia                   Serbia                  
## [1335] Serbia                   Serbia                  
## [1337] Serbia                   Serbia                  
## [1339] Serbia                   Serbia                  
## [1341] Serbia                   Serbia                  
## [1343] Serbia                   Serbia                  
## [1345] Sierra Leone             Sierra Leone            
## [1347] Sierra Leone             Sierra Leone            
## [1349] Sierra Leone             Sierra Leone            
## [1351] Sierra Leone             Sierra Leone            
## [1353] Sierra Leone             Sierra Leone            
## [1355] Sierra Leone             Sierra Leone            
## [1357] Singapore                Singapore               
## [1359] Singapore                Singapore               
## [1361] Singapore                Singapore               
## [1363] Singapore                Singapore               
## [1365] Singapore                Singapore               
## [1367] Singapore                Singapore               
## [1369] Slovak Republic          Slovak Republic         
## [1371] Slovak Republic          Slovak Republic         
## [1373] Slovak Republic          Slovak Republic         
## [1375] Slovak Republic          Slovak Republic         
## [1377] Slovak Republic          Slovak Republic         
## [1379] Slovak Republic          Slovak Republic         
## [1381] Slovenia                 Slovenia                
## [1383] Slovenia                 Slovenia                
## [1385] Slovenia                 Slovenia                
## [1387] Slovenia                 Slovenia                
## [1389] Slovenia                 Slovenia                
## [1391] Slovenia                 Slovenia                
## [1393] Somalia                  Somalia                 
## [1395] Somalia                  Somalia                 
## [1397] Somalia                  Somalia                 
## [1399] Somalia                  Somalia                 
## [1401] Somalia                  Somalia                 
## [1403] Somalia                  Somalia                 
## [1405] South Africa             South Africa            
## [1407] South Africa             South Africa            
## [1409] South Africa             South Africa            
## [1411] South Africa             South Africa            
## [1413] South Africa             South Africa            
## [1415] South Africa             South Africa            
## [1417] Spain                    Spain                   
## [1419] Spain                    Spain                   
## [1421] Spain                    Spain                   
## [1423] Spain                    Spain                   
## [1425] Spain                    Spain                   
## [1427] Spain                    Spain                   
## [1429] Sri Lanka                Sri Lanka               
## [1431] Sri Lanka                Sri Lanka               
## [1433] Sri Lanka                Sri Lanka               
## [1435] Sri Lanka                Sri Lanka               
## [1437] Sri Lanka                Sri Lanka               
## [1439] Sri Lanka                Sri Lanka               
## [1441] Sudan                    Sudan                   
## [1443] Sudan                    Sudan                   
## [1445] Sudan                    Sudan                   
## [1447] Sudan                    Sudan                   
## [1449] Sudan                    Sudan                   
## [1451] Sudan                    Sudan                   
## [1453] Swaziland                Swaziland               
## [1455] Swaziland                Swaziland               
## [1457] Swaziland                Swaziland               
## [1459] Swaziland                Swaziland               
## [1461] Swaziland                Swaziland               
## [1463] Swaziland                Swaziland               
## [1465] Sweden                   Sweden                  
## [1467] Sweden                   Sweden                  
## [1469] Sweden                   Sweden                  
## [1471] Sweden                   Sweden                  
## [1473] Sweden                   Sweden                  
## [1475] Sweden                   Sweden                  
## [1477] Switzerland              Switzerland             
## [1479] Switzerland              Switzerland             
## [1481] Switzerland              Switzerland             
## [1483] Switzerland              Switzerland             
## [1485] Switzerland              Switzerland             
## [1487] Switzerland              Switzerland             
## [1489] Syria                    Syria                   
## [1491] Syria                    Syria                   
## [1493] Syria                    Syria                   
## [1495] Syria                    Syria                   
## [1497] Syria                    Syria                   
## [1499] Syria                    Syria                   
## [1501] Taiwan                   Taiwan                  
## [1503] Taiwan                   Taiwan                  
## [1505] Taiwan                   Taiwan                  
## [1507] Taiwan                   Taiwan                  
## [1509] Taiwan                   Taiwan                  
## [1511] Taiwan                   Taiwan                  
## [1513] Tanzania                 Tanzania                
## [1515] Tanzania                 Tanzania                
## [1517] Tanzania                 Tanzania                
## [1519] Tanzania                 Tanzania                
## [1521] Tanzania                 Tanzania                
## [1523] Tanzania                 Tanzania                
## [1525] Thailand                 Thailand                
## [1527] Thailand                 Thailand                
## [1529] Thailand                 Thailand                
## [1531] Thailand                 Thailand                
## [1533] Thailand                 Thailand                
## [1535] Thailand                 Thailand                
## [1537] Togo                     Togo                    
## [1539] Togo                     Togo                    
## [1541] Togo                     Togo                    
## [1543] Togo                     Togo                    
## [1545] Togo                     Togo                    
## [1547] Togo                     Togo                    
## [1549] Trinidad and Tobago      Trinidad and Tobago     
## [1551] Trinidad and Tobago      Trinidad and Tobago     
## [1553] Trinidad and Tobago      Trinidad and Tobago     
## [1555] Trinidad and Tobago      Trinidad and Tobago     
## [1557] Trinidad and Tobago      Trinidad and Tobago     
## [1559] Trinidad and Tobago      Trinidad and Tobago     
## [1561] Tunisia                  Tunisia                 
## [1563] Tunisia                  Tunisia                 
## [1565] Tunisia                  Tunisia                 
## [1567] Tunisia                  Tunisia                 
## [1569] Tunisia                  Tunisia                 
## [1571] Tunisia                  Tunisia                 
## [1573] Turkey                   Turkey                  
## [1575] Turkey                   Turkey                  
## [1577] Turkey                   Turkey                  
## [1579] Turkey                   Turkey                  
## [1581] Turkey                   Turkey                  
## [1583] Turkey                   Turkey                  
## [1585] Uganda                   Uganda                  
## [1587] Uganda                   Uganda                  
## [1589] Uganda                   Uganda                  
## [1591] Uganda                   Uganda                  
## [1593] Uganda                   Uganda                  
## [1595] Uganda                   Uganda                  
## [1597] United Kingdom           United Kingdom          
## [1599] United Kingdom           United Kingdom          
## [1601] United Kingdom           United Kingdom          
## [1603] United Kingdom           United Kingdom          
## [1605] United Kingdom           United Kingdom          
## [1607] United Kingdom           United Kingdom          
## [1609] United States            United States           
## [1611] United States            United States           
## [1613] United States            United States           
## [1615] United States            United States           
## [1617] United States            United States           
## [1619] United States            United States           
## [1621] Uruguay                  Uruguay                 
## [1623] Uruguay                  Uruguay                 
## [1625] Uruguay                  Uruguay                 
## [1627] Uruguay                  Uruguay                 
## [1629] Uruguay                  Uruguay                 
## [1631] Uruguay                  Uruguay                 
## [1633] Venezuela                Venezuela               
## [1635] Venezuela                Venezuela               
## [1637] Venezuela                Venezuela               
## [1639] Venezuela                Venezuela               
## [1641] Venezuela                Venezuela               
## [1643] Venezuela                Venezuela               
## [1645] Vietnam                  Vietnam                 
## [1647] Vietnam                  Vietnam                 
## [1649] Vietnam                  Vietnam                 
## [1651] Vietnam                  Vietnam                 
## [1653] Vietnam                  Vietnam                 
## [1655] Vietnam                  Vietnam                 
## [1657] West Bank and Gaza       West Bank and Gaza      
## [1659] West Bank and Gaza       West Bank and Gaza      
## [1661] West Bank and Gaza       West Bank and Gaza      
## [1663] West Bank and Gaza       West Bank and Gaza      
## [1665] West Bank and Gaza       West Bank and Gaza      
## [1667] West Bank and Gaza       West Bank and Gaza      
## [1669] Yemen, Rep.              Yemen, Rep.             
## [1671] Yemen, Rep.              Yemen, Rep.             
## [1673] Yemen, Rep.              Yemen, Rep.             
## [1675] Yemen, Rep.              Yemen, Rep.             
## [1677] Yemen, Rep.              Yemen, Rep.             
## [1679] Yemen, Rep.              Yemen, Rep.             
## [1681] Zambia                   Zambia                  
## [1683] Zambia                   Zambia                  
## [1685] Zambia                   Zambia                  
## [1687] Zambia                   Zambia                  
## [1689] Zambia                   Zambia                  
## [1691] Zambia                   Zambia                  
## [1693] Zimbabwe                 Zimbabwe                
## [1695] Zimbabwe                 Zimbabwe                
## [1697] Zimbabwe                 Zimbabwe                
## [1699] Zimbabwe                 Zimbabwe                
## [1701] Zimbabwe                 Zimbabwe                
## [1703] Zimbabwe                 Zimbabwe                
## 142 Levels: Afghanistan Albania Algeria Angola Argentina ... Zimbabwe
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
head(gapminder)
```

```
##       country continent year lifeExp      pop gdpPercap
## 1 Afghanistan      Asia 1952  28.801  8425333  779.4453
## 2 Afghanistan      Asia 1957  30.332  9240934  820.8530
## 3 Afghanistan      Asia 1962  31.997 10267083  853.1007
## 4 Afghanistan      Asia 1967  34.020 11537966  836.1971
## 5 Afghanistan      Asia 1972  36.088 13079460  739.9811
## 6 Afghanistan      Asia 1977  38.438 14880372  786.1134
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
gapminder[3, ]
```

```
##       country continent year lifeExp      pop gdpPercap
## 3 Afghanistan      Asia 1962  31.997 10267083  853.1007
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
gapminder[2, 3]
```

```
## [1] 1957
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
gapminder[-(1:1650), 3]
```

```
##  [1] 1982 1987 1992 1997 2002 2007 1952 1957 1962 1967 1972 1977 1982 1987
## [15] 1992 1997 2002 2007 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997
## [29] 2002 2007 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007
## [43] 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
gapminder[c(2,4), -3]
```

```
##       country continent lifeExp      pop gdpPercap
## 2 Afghanistan      Asia  30.332  9240934  820.8530
## 4 Afghanistan      Asia  34.020 11537966  836.1971
```

---
## data.frame - indexing

- `[]` operator can be used to subset rows and columns
- `[]` operator requires two arguments - one for rows (observations) and one for columns (variables) - `[rows, columns]`


```r
gapminder[c(2,4), c("country", "pop")]
```

```
##       country      pop
## 2 Afghanistan  9240934
## 4 Afghanistan 11537966
```

---
## data.frame - indexing

- Logical operators, such as `==, !=, &gt;, &gt;=, &lt;, &lt;=, &amp;, |` can also be used for indexing


```r
gapminder[gapminder$lifeExp&gt;82, c("country", "pop")]
```

```
##              country       pop
## 672 Hong Kong, China   6980412
## 804            Japan 127467972
```


```r
subset(gapminder, pop&gt;1000000000)
```

```
##     country continent year lifeExp        pop gdpPercap
## 295   China      Asia 1982  65.525 1000281000  962.4214
## 296   China      Asia 1987  67.274 1084035000 1378.9040
## 297   China      Asia 1992  68.690 1164970000 1655.7842
## 298   China      Asia 1997  70.426 1230075000 2289.2341
## 299   China      Asia 2002  72.028 1280400000 3119.2809
## 300   China      Asia 2007  72.961 1318683096 4959.1149
## 707   India      Asia 2002  62.879 1034172547 1746.7695
## 708   India      Asia 2007  64.698 1110396331 2452.2104
```

---
## data.frame - indexing

- Logical operators, such as `==, !=, &gt;, &gt;=, &lt;, &lt;=, &amp;, |` can also be used for indexing


```r
subset(gapminder, pop&gt;1000000000 &amp; country=='India')
```

```
##     country continent year lifeExp        pop gdpPercap
## 707   India      Asia 2002  62.879 1034172547  1746.769
## 708   India      Asia 2007  64.698 1110396331  2452.210
```


```r
subset(gapminder, pop&gt;1000000000 | continent=='Oceania')
```

```
##          country continent year lifeExp        pop  gdpPercap
## 61     Australia   Oceania 1952  69.120    8691212 10039.5956
## 62     Australia   Oceania 1957  70.330    9712569 10949.6496
## 63     Australia   Oceania 1962  70.930   10794968 12217.2269
## 64     Australia   Oceania 1967  71.100   11872264 14526.1246
## 65     Australia   Oceania 1972  71.930   13177000 16788.6295
## 66     Australia   Oceania 1977  73.490   14074100 18334.1975
## 67     Australia   Oceania 1982  74.740   15184200 19477.0093
## 68     Australia   Oceania 1987  76.320   16257249 21888.8890
## 69     Australia   Oceania 1992  77.560   17481977 23424.7668
## 70     Australia   Oceania 1997  78.830   18565243 26997.9366
## 71     Australia   Oceania 2002  80.370   19546792 30687.7547
## 72     Australia   Oceania 2007  81.235   20434176 34435.3674
## 295        China      Asia 1982  65.525 1000281000   962.4214
## 296        China      Asia 1987  67.274 1084035000  1378.9040
## 297        China      Asia 1992  68.690 1164970000  1655.7842
## 298        China      Asia 1997  70.426 1230075000  2289.2341
## 299        China      Asia 2002  72.028 1280400000  3119.2809
## 300        China      Asia 2007  72.961 1318683096  4959.1149
## 707        India      Asia 2002  62.879 1034172547  1746.7695
## 708        India      Asia 2007  64.698 1110396331  2452.2104
## 1093 New Zealand   Oceania 1952  69.390    1994794 10556.5757
## 1094 New Zealand   Oceania 1957  70.260    2229407 12247.3953
## 1095 New Zealand   Oceania 1962  71.240    2488550 13175.6780
## 1096 New Zealand   Oceania 1967  71.520    2728150 14463.9189
## 1097 New Zealand   Oceania 1972  71.890    2929100 16046.0373
## 1098 New Zealand   Oceania 1977  72.220    3164900 16233.7177
## 1099 New Zealand   Oceania 1982  73.840    3210650 17632.4104
## 1100 New Zealand   Oceania 1987  74.320    3317166 19007.1913
## 1101 New Zealand   Oceania 1992  76.330    3437674 18363.3249
## 1102 New Zealand   Oceania 1997  77.550    3676187 21050.4138
## 1103 New Zealand   Oceania 2002  79.110    3908037 23189.8014
## 1104 New Zealand   Oceania 2007  80.204    4115771 25185.0091
```

---
## data.frame - indexing

- A new object can be created from the results of indexing


```r
africa &lt;- subset(gapminder, continent=='Africa')
africa
```

```
##                       country continent year lifeExp       pop  gdpPercap
## 25                    Algeria    Africa 1952  43.077   9279525  2449.0082
## 26                    Algeria    Africa 1957  45.685  10270856  3013.9760
## 27                    Algeria    Africa 1962  48.303  11000948  2550.8169
## 28                    Algeria    Africa 1967  51.407  12760499  3246.9918
## 29                    Algeria    Africa 1972  54.518  14760787  4182.6638
## 30                    Algeria    Africa 1977  58.014  17152804  4910.4168
## 31                    Algeria    Africa 1982  61.368  20033753  5745.1602
## 32                    Algeria    Africa 1987  65.799  23254956  5681.3585
## 33                    Algeria    Africa 1992  67.744  26298373  5023.2166
## 34                    Algeria    Africa 1997  69.152  29072015  4797.2951
## 35                    Algeria    Africa 2002  70.994  31287142  5288.0404
## 36                    Algeria    Africa 2007  72.301  33333216  6223.3675
## 37                     Angola    Africa 1952  30.015   4232095  3520.6103
## 38                     Angola    Africa 1957  31.999   4561361  3827.9405
## 39                     Angola    Africa 1962  34.000   4826015  4269.2767
## 40                     Angola    Africa 1967  35.985   5247469  5522.7764
## 41                     Angola    Africa 1972  37.928   5894858  5473.2880
## 42                     Angola    Africa 1977  39.483   6162675  3008.6474
## 43                     Angola    Africa 1982  39.942   7016384  2756.9537
## 44                     Angola    Africa 1987  39.906   7874230  2430.2083
## 45                     Angola    Africa 1992  40.647   8735988  2627.8457
## 46                     Angola    Africa 1997  40.963   9875024  2277.1409
## 47                     Angola    Africa 2002  41.003  10866106  2773.2873
## 48                     Angola    Africa 2007  42.731  12420476  4797.2313
## 121                     Benin    Africa 1952  38.223   1738315  1062.7522
## 122                     Benin    Africa 1957  40.358   1925173   959.6011
## 123                     Benin    Africa 1962  42.618   2151895   949.4991
## 124                     Benin    Africa 1967  44.885   2427334  1035.8314
## 125                     Benin    Africa 1972  47.014   2761407  1085.7969
## 126                     Benin    Africa 1977  49.190   3168267  1029.1613
## 127                     Benin    Africa 1982  50.904   3641603  1277.8976
## 128                     Benin    Africa 1987  52.337   4243788  1225.8560
## 129                     Benin    Africa 1992  53.919   4981671  1191.2077
## 130                     Benin    Africa 1997  54.777   6066080  1232.9753
## 131                     Benin    Africa 2002  54.406   7026113  1372.8779
## 132                     Benin    Africa 2007  56.728   8078314  1441.2849
## 157                  Botswana    Africa 1952  47.622    442308   851.2411
## 158                  Botswana    Africa 1957  49.618    474639   918.2325
## 159                  Botswana    Africa 1962  51.520    512764   983.6540
## 160                  Botswana    Africa 1967  53.298    553541  1214.7093
## 161                  Botswana    Africa 1972  56.024    619351  2263.6111
## 162                  Botswana    Africa 1977  59.319    781472  3214.8578
## 163                  Botswana    Africa 1982  61.484    970347  4551.1421
## 164                  Botswana    Africa 1987  63.622   1151184  6205.8839
## 165                  Botswana    Africa 1992  62.745   1342614  7954.1116
## 166                  Botswana    Africa 1997  52.556   1536536  8647.1423
## 167                  Botswana    Africa 2002  46.634   1630347 11003.6051
## 168                  Botswana    Africa 2007  50.728   1639131 12569.8518
## 193              Burkina Faso    Africa 1952  31.975   4469979   543.2552
## 194              Burkina Faso    Africa 1957  34.906   4713416   617.1835
## 195              Burkina Faso    Africa 1962  37.814   4919632   722.5120
## 196              Burkina Faso    Africa 1967  40.697   5127935   794.8266
## 197              Burkina Faso    Africa 1972  43.591   5433886   854.7360
## 198              Burkina Faso    Africa 1977  46.137   5889574   743.3870
## 199              Burkina Faso    Africa 1982  48.122   6634596   807.1986
## 200              Burkina Faso    Africa 1987  49.557   7586551   912.0631
## 201              Burkina Faso    Africa 1992  50.260   8878303   931.7528
## 202              Burkina Faso    Africa 1997  50.324  10352843   946.2950
## 203              Burkina Faso    Africa 2002  50.650  12251209  1037.6452
## 204              Burkina Faso    Africa 2007  52.295  14326203  1217.0330
## 205                   Burundi    Africa 1952  39.031   2445618   339.2965
## 206                   Burundi    Africa 1957  40.533   2667518   379.5646
## 207                   Burundi    Africa 1962  42.045   2961915   355.2032
## 208                   Burundi    Africa 1967  43.548   3330989   412.9775
## 209                   Burundi    Africa 1972  44.057   3529983   464.0995
## 210                   Burundi    Africa 1977  45.910   3834415   556.1033
## 211                   Burundi    Africa 1982  47.471   4580410   559.6032
## 212                   Burundi    Africa 1987  48.211   5126023   621.8188
## 213                   Burundi    Africa 1992  44.736   5809236   631.6999
## 214                   Burundi    Africa 1997  45.326   6121610   463.1151
## 215                   Burundi    Africa 2002  47.360   7021078   446.4035
## 216                   Burundi    Africa 2007  49.580   8390505   430.0707
## 229                  Cameroon    Africa 1952  38.523   5009067  1172.6677
## 230                  Cameroon    Africa 1957  40.428   5359923  1313.0481
## 231                  Cameroon    Africa 1962  42.643   5793633  1399.6074
## 232                  Cameroon    Africa 1967  44.799   6335506  1508.4531
## 233                  Cameroon    Africa 1972  47.049   7021028  1684.1465
## 234                  Cameroon    Africa 1977  49.355   7959865  1783.4329
## 235                  Cameroon    Africa 1982  52.961   9250831  2367.9833
## 236                  Cameroon    Africa 1987  54.985  10780667  2602.6642
## 237                  Cameroon    Africa 1992  54.314  12467171  1793.1633
## 238                  Cameroon    Africa 1997  52.199  14195809  1694.3375
## 239                  Cameroon    Africa 2002  49.856  15929988  1934.0114
## 240                  Cameroon    Africa 2007  50.430  17696293  2042.0952
## 253  Central African Republic    Africa 1952  35.463   1291695  1071.3107
## 254  Central African Republic    Africa 1957  37.464   1392284  1190.8443
## 255  Central African Republic    Africa 1962  39.475   1523478  1193.0688
## 256  Central African Republic    Africa 1967  41.478   1733638  1136.0566
## 257  Central African Republic    Africa 1972  43.457   1927260  1070.0133
## 258  Central African Republic    Africa 1977  46.775   2167533  1109.3743
## 259  Central African Republic    Africa 1982  48.295   2476971   956.7530
## 260  Central African Republic    Africa 1987  50.485   2840009   844.8764
## 261  Central African Republic    Africa 1992  49.396   3265124   747.9055
## 262  Central African Republic    Africa 1997  46.066   3696513   740.5063
## 263  Central African Republic    Africa 2002  43.308   4048013   738.6906
## 264  Central African Republic    Africa 2007  44.741   4369038   706.0165
## 265                      Chad    Africa 1952  38.092   2682462  1178.6659
## 266                      Chad    Africa 1957  39.881   2894855  1308.4956
## 267                      Chad    Africa 1962  41.716   3150417  1389.8176
## 268                      Chad    Africa 1967  43.601   3495967  1196.8106
## 269                      Chad    Africa 1972  45.569   3899068  1104.1040
## 270                      Chad    Africa 1977  47.383   4388260  1133.9850
## 271                      Chad    Africa 1982  49.517   4875118   797.9081
## 272                      Chad    Africa 1987  51.051   5498955   952.3861
## 273                      Chad    Africa 1992  51.724   6429417  1058.0643
## 274                      Chad    Africa 1997  51.573   7562011  1004.9614
## 275                      Chad    Africa 2002  50.525   8835739  1156.1819
## 276                      Chad    Africa 2007  50.651  10238807  1704.0637
## 313                   Comoros    Africa 1952  40.715    153936  1102.9909
## 314                   Comoros    Africa 1957  42.460    170928  1211.1485
## 315                   Comoros    Africa 1962  44.467    191689  1406.6483
## 316                   Comoros    Africa 1967  46.472    217378  1876.0296
## 317                   Comoros    Africa 1972  48.944    250027  1937.5777
## 318                   Comoros    Africa 1977  50.939    304739  1172.6030
## 319                   Comoros    Africa 1982  52.933    348643  1267.1001
## 320                   Comoros    Africa 1987  54.926    395114  1315.9808
## 321                   Comoros    Africa 1992  57.939    454429  1246.9074
## 322                   Comoros    Africa 1997  60.660    527982  1173.6182
## 323                   Comoros    Africa 2002  62.974    614382  1075.8116
## 324                   Comoros    Africa 2007  65.152    710960   986.1479
## 325          Congo, Dem. Rep.    Africa 1952  39.143  14100005   780.5423
## 326          Congo, Dem. Rep.    Africa 1957  40.652  15577932   905.8602
## 327          Congo, Dem. Rep.    Africa 1962  42.122  17486434   896.3146
## 328          Congo, Dem. Rep.    Africa 1967  44.056  19941073   861.5932
## 329          Congo, Dem. Rep.    Africa 1972  45.989  23007669   904.8961
## 330          Congo, Dem. Rep.    Africa 1977  47.804  26480870   795.7573
## 331          Congo, Dem. Rep.    Africa 1982  47.784  30646495   673.7478
## 332          Congo, Dem. Rep.    Africa 1987  47.412  35481645   672.7748
## 333          Congo, Dem. Rep.    Africa 1992  45.548  41672143   457.7192
## 334          Congo, Dem. Rep.    Africa 1997  42.587  47798986   312.1884
## 335          Congo, Dem. Rep.    Africa 2002  44.966  55379852   241.1659
## 336          Congo, Dem. Rep.    Africa 2007  46.462  64606759   277.5519
## 337               Congo, Rep.    Africa 1952  42.111    854885  2125.6214
## 338               Congo, Rep.    Africa 1957  45.053    940458  2315.0566
## 339               Congo, Rep.    Africa 1962  48.435   1047924  2464.7832
## 340               Congo, Rep.    Africa 1967  52.040   1179760  2677.9396
## 341               Congo, Rep.    Africa 1972  54.907   1340458  3213.1527
## 342               Congo, Rep.    Africa 1977  55.625   1536769  3259.1790
## 343               Congo, Rep.    Africa 1982  56.695   1774735  4879.5075
## 344               Congo, Rep.    Africa 1987  57.470   2064095  4201.1949
## 345               Congo, Rep.    Africa 1992  56.433   2409073  4016.2395
## 346               Congo, Rep.    Africa 1997  52.962   2800947  3484.1644
## 347               Congo, Rep.    Africa 2002  52.970   3328795  3484.0620
## 348               Congo, Rep.    Africa 2007  55.322   3800610  3632.5578
## 361             Cote d'Ivoire    Africa 1952  40.477   2977019  1388.5947
## 362             Cote d'Ivoire    Africa 1957  42.469   3300000  1500.8959
## 363             Cote d'Ivoire    Africa 1962  44.930   3832408  1728.8694
## 364             Cote d'Ivoire    Africa 1967  47.350   4744870  2052.0505
## 365             Cote d'Ivoire    Africa 1972  49.801   6071696  2378.2011
## 366             Cote d'Ivoire    Africa 1977  52.374   7459574  2517.7365
## 367             Cote d'Ivoire    Africa 1982  53.983   9025951  2602.7102
## 368             Cote d'Ivoire    Africa 1987  54.655  10761098  2156.9561
## 369             Cote d'Ivoire    Africa 1992  52.044  12772596  1648.0738
## 370             Cote d'Ivoire    Africa 1997  47.991  14625967  1786.2654
## 371             Cote d'Ivoire    Africa 2002  46.832  16252726  1648.8008
## 372             Cote d'Ivoire    Africa 2007  48.328  18013409  1544.7501
## 421                  Djibouti    Africa 1952  34.812     63149  2669.5295
## 422                  Djibouti    Africa 1957  37.328     71851  2864.9691
## 423                  Djibouti    Africa 1962  39.693     89898  3020.9893
## 424                  Djibouti    Africa 1967  42.074    127617  3020.0505
## 425                  Djibouti    Africa 1972  44.366    178848  3694.2124
## 426                  Djibouti    Africa 1977  46.519    228694  3081.7610
## 427                  Djibouti    Africa 1982  48.812    305991  2879.4681
## 428                  Djibouti    Africa 1987  50.040    311025  2880.1026
## 429                  Djibouti    Africa 1992  51.604    384156  2377.1562
## 430                  Djibouti    Africa 1997  53.157    417908  1895.0170
## 431                  Djibouti    Africa 2002  53.373    447416  1908.2609
## 432                  Djibouti    Africa 2007  54.791    496374  2082.4816
## 457                     Egypt    Africa 1952  41.893  22223309  1418.8224
## 458                     Egypt    Africa 1957  44.444  25009741  1458.9153
## 459                     Egypt    Africa 1962  46.992  28173309  1693.3359
## 460                     Egypt    Africa 1967  49.293  31681188  1814.8807
## 461                     Egypt    Africa 1972  51.137  34807417  2024.0081
## 462                     Egypt    Africa 1977  53.319  38783863  2785.4936
## 463                     Egypt    Africa 1982  56.006  45681811  3503.7296
## 464                     Egypt    Africa 1987  59.797  52799062  3885.4607
## 465                     Egypt    Africa 1992  63.674  59402198  3794.7552
## 466                     Egypt    Africa 1997  67.217  66134291  4173.1818
## 467                     Egypt    Africa 2002  69.806  73312559  4754.6044
## 468                     Egypt    Africa 2007  71.338  80264543  5581.1810
## 481         Equatorial Guinea    Africa 1952  34.482    216964   375.6431
## 482         Equatorial Guinea    Africa 1957  35.983    232922   426.0964
## 483         Equatorial Guinea    Africa 1962  37.485    249220   582.8420
## 484         Equatorial Guinea    Africa 1967  38.987    259864   915.5960
## 485         Equatorial Guinea    Africa 1972  40.516    277603   672.4123
## 486         Equatorial Guinea    Africa 1977  42.024    192675   958.5668
## 487         Equatorial Guinea    Africa 1982  43.662    285483   927.8253
## 488         Equatorial Guinea    Africa 1987  45.664    341244   966.8968
## 489         Equatorial Guinea    Africa 1992  47.545    387838  1132.0550
## 490         Equatorial Guinea    Africa 1997  48.245    439971  2814.4808
## 491         Equatorial Guinea    Africa 2002  49.348    495627  7703.4959
## 492         Equatorial Guinea    Africa 2007  51.579    551201 12154.0897
## 493                   Eritrea    Africa 1952  35.928   1438760   328.9406
## 494                   Eritrea    Africa 1957  38.047   1542611   344.1619
## 495                   Eritrea    Africa 1962  40.158   1666618   380.9958
## 496                   Eritrea    Africa 1967  42.189   1820319   468.7950
## 497                   Eritrea    Africa 1972  44.142   2260187   514.3242
## 498                   Eritrea    Africa 1977  44.535   2512642   505.7538
## 499                   Eritrea    Africa 1982  43.890   2637297   524.8758
## 500                   Eritrea    Africa 1987  46.453   2915959   521.1341
## 501                   Eritrea    Africa 1992  49.991   3668440   582.8585
## 502                   Eritrea    Africa 1997  53.378   4058319   913.4708
## 503                   Eritrea    Africa 2002  55.240   4414865   765.3500
## 504                   Eritrea    Africa 2007  58.040   4906585   641.3695
## 505                  Ethiopia    Africa 1952  34.078  20860941   362.1463
## 506                  Ethiopia    Africa 1957  36.667  22815614   378.9042
## 507                  Ethiopia    Africa 1962  40.059  25145372   419.4564
## 508                  Ethiopia    Africa 1967  42.115  27860297   516.1186
## 509                  Ethiopia    Africa 1972  43.515  30770372   566.2439
## 510                  Ethiopia    Africa 1977  44.510  34617799   556.8084
## 511                  Ethiopia    Africa 1982  44.916  38111756   577.8607
## 512                  Ethiopia    Africa 1987  46.684  42999530   573.7413
## 513                  Ethiopia    Africa 1992  48.091  52088559   421.3535
## 514                  Ethiopia    Africa 1997  49.402  59861301   515.8894
## 515                  Ethiopia    Africa 2002  50.725  67946797   530.0535
## 516                  Ethiopia    Africa 2007  52.947  76511887   690.8056
## 541                     Gabon    Africa 1952  37.003    420702  4293.4765
## 542                     Gabon    Africa 1957  38.999    434904  4976.1981
## 543                     Gabon    Africa 1962  40.489    455661  6631.4592
## 544                     Gabon    Africa 1967  44.598    489004  8358.7620
## 545                     Gabon    Africa 1972  48.690    537977 11401.9484
## 546                     Gabon    Africa 1977  52.790    706367 21745.5733
## 547                     Gabon    Africa 1982  56.564    753874 15113.3619
## 548                     Gabon    Africa 1987  60.190    880397 11864.4084
## 549                     Gabon    Africa 1992  61.366    985739 13522.1575
## 550                     Gabon    Africa 1997  60.461   1126189 14722.8419
## 551                     Gabon    Africa 2002  56.761   1299304 12521.7139
## 552                     Gabon    Africa 2007  56.735   1454867 13206.4845
## 553                    Gambia    Africa 1952  30.000    284320   485.2307
## 554                    Gambia    Africa 1957  32.065    323150   520.9267
## 555                    Gambia    Africa 1962  33.896    374020   599.6503
## 556                    Gambia    Africa 1967  35.857    439593   734.7829
## 557                    Gambia    Africa 1972  38.308    517101   756.0868
## 558                    Gambia    Africa 1977  41.842    608274   884.7553
## 559                    Gambia    Africa 1982  45.580    715523   835.8096
## 560                    Gambia    Africa 1987  49.265    848406   611.6589
## 561                    Gambia    Africa 1992  52.644   1025384   665.6244
## 562                    Gambia    Africa 1997  55.861   1235767   653.7302
## 563                    Gambia    Africa 2002  58.041   1457766   660.5856
## 564                    Gambia    Africa 2007  59.448   1688359   752.7497
## 577                     Ghana    Africa 1952  43.149   5581001   911.2989
## 578                     Ghana    Africa 1957  44.779   6391288  1043.5615
## 579                     Ghana    Africa 1962  46.452   7355248  1190.0411
## 580                     Ghana    Africa 1967  48.072   8490213  1125.6972
## 581                     Ghana    Africa 1972  49.875   9354120  1178.2237
## 582                     Ghana    Africa 1977  51.756  10538093   993.2240
## 583                     Ghana    Africa 1982  53.744  11400338   876.0326
## 584                     Ghana    Africa 1987  55.729  14168101   847.0061
## 585                     Ghana    Africa 1992  57.501  16278738   925.0602
## 586                     Ghana    Africa 1997  58.556  18418288  1005.2458
## 587                     Ghana    Africa 2002  58.453  20550751  1111.9846
## 588                     Ghana    Africa 2007  60.022  22873338  1327.6089
## 613                    Guinea    Africa 1952  33.609   2664249   510.1965
## 614                    Guinea    Africa 1957  34.558   2876726   576.2670
## 615                    Guinea    Africa 1962  35.753   3140003   686.3737
## 616                    Guinea    Africa 1967  37.197   3451418   708.7595
## 617                    Guinea    Africa 1972  38.842   3811387   741.6662
## 618                    Guinea    Africa 1977  40.762   4227026   874.6859
## 619                    Guinea    Africa 1982  42.891   4710497   857.2504
## 620                    Guinea    Africa 1987  45.552   5650262   805.5725
## 621                    Guinea    Africa 1992  48.576   6990574   794.3484
## 622                    Guinea    Africa 1997  51.455   8048834   869.4498
## 623                    Guinea    Africa 2002  53.676   8807818   945.5836
## 624                    Guinea    Africa 2007  56.007   9947814   942.6542
## 625             Guinea-Bissau    Africa 1952  32.500    580653   299.8503
## 626             Guinea-Bissau    Africa 1957  33.489    601095   431.7905
## 627             Guinea-Bissau    Africa 1962  34.488    627820   522.0344
## 628             Guinea-Bissau    Africa 1967  35.492    601287   715.5806
## 629             Guinea-Bissau    Africa 1972  36.486    625361   820.2246
## 630             Guinea-Bissau    Africa 1977  37.465    745228   764.7260
## 631             Guinea-Bissau    Africa 1982  39.327    825987   838.1240
## 632             Guinea-Bissau    Africa 1987  41.245    927524   736.4154
## 633             Guinea-Bissau    Africa 1992  43.266   1050938   745.5399
## 634             Guinea-Bissau    Africa 1997  44.873   1193708   796.6645
## 635             Guinea-Bissau    Africa 2002  45.504   1332459   575.7047
## 636             Guinea-Bissau    Africa 2007  46.388   1472041   579.2317
## 817                     Kenya    Africa 1952  42.270   6464046   853.5409
## 818                     Kenya    Africa 1957  44.686   7454779   944.4383
## 819                     Kenya    Africa 1962  47.949   8678557   896.9664
## 820                     Kenya    Africa 1967  50.654  10191512  1056.7365
## 821                     Kenya    Africa 1972  53.559  12044785  1222.3600
## 822                     Kenya    Africa 1977  56.155  14500404  1267.6132
## 823                     Kenya    Africa 1982  58.766  17661452  1348.2258
## 824                     Kenya    Africa 1987  59.339  21198082  1361.9369
## 825                     Kenya    Africa 1992  59.285  25020539  1341.9217
## 826                     Kenya    Africa 1997  54.407  28263827  1360.4850
## 827                     Kenya    Africa 2002  50.992  31386842  1287.5147
## 828                     Kenya    Africa 2007  54.110  35610177  1463.2493
## 877                   Lesotho    Africa 1952  42.138    748747   298.8462
## 878                   Lesotho    Africa 1957  45.047    813338   335.9971
## 879                   Lesotho    Africa 1962  47.747    893143   411.8006
## 880                   Lesotho    Africa 1967  48.492    996380   498.6390
## 881                   Lesotho    Africa 1972  49.767   1116779   496.5816
## 882                   Lesotho    Africa 1977  52.208   1251524   745.3695
## 883                   Lesotho    Africa 1982  55.078   1411807   797.2631
## 884                   Lesotho    Africa 1987  57.180   1599200   773.9932
## 885                   Lesotho    Africa 1992  59.685   1803195   977.4863
## 886                   Lesotho    Africa 1997  55.558   1982823  1186.1480
## 887                   Lesotho    Africa 2002  44.593   2046772  1275.1846
## 888                   Lesotho    Africa 2007  42.592   2012649  1569.3314
## 889                   Liberia    Africa 1952  38.480    863308   575.5730
## 890                   Liberia    Africa 1957  39.486    975950   620.9700
## 891                   Liberia    Africa 1962  40.502   1112796   634.1952
## 892                   Liberia    Africa 1967  41.536   1279406   713.6036
## 893                   Liberia    Africa 1972  42.614   1482628   803.0055
## 894                   Liberia    Africa 1977  43.764   1703617   640.3224
## 895                   Liberia    Africa 1982  44.852   1956875   572.1996
## 896                   Liberia    Africa 1987  46.027   2269414   506.1139
## 897                   Liberia    Africa 1992  40.802   1912974   636.6229
## 898                   Liberia    Africa 1997  42.221   2200725   609.1740
## 899                   Liberia    Africa 2002  43.753   2814651   531.4824
## 900                   Liberia    Africa 2007  45.678   3193942   414.5073
## 901                     Libya    Africa 1952  42.723   1019729  2387.5481
## 902                     Libya    Africa 1957  45.289   1201578  3448.2844
## 903                     Libya    Africa 1962  47.808   1441863  6757.0308
## 904                     Libya    Africa 1967  50.227   1759224 18772.7517
## 905                     Libya    Africa 1972  52.773   2183877 21011.4972
## 906                     Libya    Africa 1977  57.442   2721783 21951.2118
## 907                     Libya    Africa 1982  62.155   3344074 17364.2754
## 908                     Libya    Africa 1987  66.234   3799845 11770.5898
## 909                     Libya    Africa 1992  68.755   4364501  9640.1385
## 910                     Libya    Africa 1997  71.555   4759670  9467.4461
## 911                     Libya    Africa 2002  72.737   5368585  9534.6775
## 912                     Libya    Africa 2007  73.952   6036914 12057.4993
## 913                Madagascar    Africa 1952  36.681   4762912  1443.0117
## 914                Madagascar    Africa 1957  38.865   5181679  1589.2027
## 915                Madagascar    Africa 1962  40.848   5703324  1643.3871
## 916                Madagascar    Africa 1967  42.881   6334556  1634.0473
## 917                Madagascar    Africa 1972  44.851   7082430  1748.5630
## 918                Madagascar    Africa 1977  46.881   8007166  1544.2286
## 919                Madagascar    Africa 1982  48.969   9171477  1302.8787
## 920                Madagascar    Africa 1987  49.350  10568642  1155.4419
## 921                Madagascar    Africa 1992  52.214  12210395  1040.6762
## 922                Madagascar    Africa 1997  54.978  14165114   986.2959
## 923                Madagascar    Africa 2002  57.286  16473477   894.6371
## 924                Madagascar    Africa 2007  59.443  19167654  1044.7701
## 925                    Malawi    Africa 1952  36.256   2917802   369.1651
## 926                    Malawi    Africa 1957  37.207   3221238   416.3698
## 927                    Malawi    Africa 1962  38.410   3628608   427.9011
## 928                    Malawi    Africa 1967  39.487   4147252   495.5148
## 929                    Malawi    Africa 1972  41.766   4730997   584.6220
## 930                    Malawi    Africa 1977  43.767   5637246   663.2237
## 931                    Malawi    Africa 1982  45.642   6502825   632.8039
## 932                    Malawi    Africa 1987  47.457   7824747   635.5174
## 933                    Malawi    Africa 1992  49.420  10014249   563.2000
## 934                    Malawi    Africa 1997  47.495  10419991   692.2758
## 935                    Malawi    Africa 2002  45.009  11824495   665.4231
## 936                    Malawi    Africa 2007  48.303  13327079   759.3499
## 949                      Mali    Africa 1952  33.685   3838168   452.3370
## 950                      Mali    Africa 1957  35.307   4241884   490.3822
## 951                      Mali    Africa 1962  36.936   4690372   496.1743
## 952                      Mali    Africa 1967  38.487   5212416   545.0099
## 953                      Mali    Africa 1972  39.977   5828158   581.3689
## 954                      Mali    Africa 1977  41.714   6491649   686.3953
## 955                      Mali    Africa 1982  43.916   6998256   618.0141
## 956                      Mali    Africa 1987  46.364   7634008   684.1716
## 957                      Mali    Africa 1992  48.388   8416215   739.0144
## 958                      Mali    Africa 1997  49.903   9384984   790.2580
## 959                      Mali    Africa 2002  51.818  10580176   951.4098
## 960                      Mali    Africa 2007  54.467  12031795  1042.5816
## 961                Mauritania    Africa 1952  40.543   1022556   743.1159
## 962                Mauritania    Africa 1957  42.338   1076852   846.1203
## 963                Mauritania    Africa 1962  44.248   1146757  1055.8960
## 964                Mauritania    Africa 1967  46.289   1230542  1421.1452
## 965                Mauritania    Africa 1972  48.437   1332786  1586.8518
## 966                Mauritania    Africa 1977  50.852   1456688  1497.4922
## 967                Mauritania    Africa 1982  53.599   1622136  1481.1502
## 968                Mauritania    Africa 1987  56.145   1841240  1421.6036
## 969                Mauritania    Africa 1992  58.333   2119465  1361.3698
## 970                Mauritania    Africa 1997  60.430   2444741  1483.1361
## 971                Mauritania    Africa 2002  62.247   2828858  1579.0195
## 972                Mauritania    Africa 2007  64.164   3270065  1803.1515
## 973                 Mauritius    Africa 1952  50.986    516556  1967.9557
## 974                 Mauritius    Africa 1957  58.089    609816  2034.0380
## 975                 Mauritius    Africa 1962  60.246    701016  2529.0675
## 976                 Mauritius    Africa 1967  61.557    789309  2475.3876
## 977                 Mauritius    Africa 1972  62.944    851334  2575.4842
## 978                 Mauritius    Africa 1977  64.930    913025  3710.9830
## 979                 Mauritius    Africa 1982  66.711    992040  3688.0377
## 980                 Mauritius    Africa 1987  68.740   1042663  4783.5869
## 981                 Mauritius    Africa 1992  69.745   1096202  6058.2538
## 982                 Mauritius    Africa 1997  70.736   1149818  7425.7053
## 983                 Mauritius    Africa 2002  71.954   1200206  9021.8159
## 984                 Mauritius    Africa 2007  72.801   1250882 10956.9911
## 1021                  Morocco    Africa 1952  42.873   9939217  1688.2036
## 1022                  Morocco    Africa 1957  45.423  11406350  1642.0023
## 1023                  Morocco    Africa 1962  47.924  13056604  1566.3535
## 1024                  Morocco    Africa 1967  50.335  14770296  1711.0448
## 1025                  Morocco    Africa 1972  52.862  16660670  1930.1950
## 1026                  Morocco    Africa 1977  55.730  18396941  2370.6200
## 1027                  Morocco    Africa 1982  59.650  20198730  2702.6204
## 1028                  Morocco    Africa 1987  62.677  22987397  2755.0470
## 1029                  Morocco    Africa 1992  65.393  25798239  2948.0473
## 1030                  Morocco    Africa 1997  67.660  28529501  2982.1019
## 1031                  Morocco    Africa 2002  69.615  31167783  3258.4956
## 1032                  Morocco    Africa 2007  71.164  33757175  3820.1752
## 1033               Mozambique    Africa 1952  31.286   6446316   468.5260
## 1034               Mozambique    Africa 1957  33.779   7038035   495.5868
## 1035               Mozambique    Africa 1962  36.161   7788944   556.6864
## 1036               Mozambique    Africa 1967  38.113   8680909   566.6692
## 1037               Mozambique    Africa 1972  40.328   9809596   724.9178
## 1038               Mozambique    Africa 1977  42.495  11127868   502.3197
## 1039               Mozambique    Africa 1982  42.795  12587223   462.2114
## 1040               Mozambique    Africa 1987  42.861  12891952   389.8762
## 1041               Mozambique    Africa 1992  44.284  13160731   410.8968
## 1042               Mozambique    Africa 1997  46.344  16603334   472.3461
## 1043               Mozambique    Africa 2002  44.026  18473780   633.6179
## 1044               Mozambique    Africa 2007  42.082  19951656   823.6856
## 1057                  Namibia    Africa 1952  41.725    485831  2423.7804
## 1058                  Namibia    Africa 1957  45.226    548080  2621.4481
## 1059                  Namibia    Africa 1962  48.386    621392  3173.2156
## 1060                  Namibia    Africa 1967  51.159    706640  3793.6948
## 1061                  Namibia    Africa 1972  53.867    821782  3746.0809
## 1062                  Namibia    Africa 1977  56.437    977026  3876.4860
## 1063                  Namibia    Africa 1982  58.968   1099010  4191.1005
## 1064                  Namibia    Africa 1987  60.835   1278184  3693.7313
## 1065                  Namibia    Africa 1992  61.999   1554253  3804.5380
## 1066                  Namibia    Africa 1997  58.909   1774766  3899.5243
## 1067                  Namibia    Africa 2002  51.479   1972153  4072.3248
## 1068                  Namibia    Africa 2007  52.906   2055080  4811.0604
## 1117                    Niger    Africa 1952  37.444   3379468   761.8794
## 1118                    Niger    Africa 1957  38.598   3692184   835.5234
## 1119                    Niger    Africa 1962  39.487   4076008   997.7661
## 1120                    Niger    Africa 1967  40.118   4534062  1054.3849
## 1121                    Niger    Africa 1972  40.546   5060262   954.2092
## 1122                    Niger    Africa 1977  41.291   5682086   808.8971
## 1123                    Niger    Africa 1982  42.598   6437188   909.7221
## 1124                    Niger    Africa 1987  44.555   7332638   668.3000
## 1125                    Niger    Africa 1992  47.391   8392818   581.1827
## 1126                    Niger    Africa 1997  51.313   9666252   580.3052
## 1127                    Niger    Africa 2002  54.496  11140655   601.0745
## 1128                    Niger    Africa 2007  56.867  12894865   619.6769
## 1129                  Nigeria    Africa 1952  36.324  33119096  1077.2819
## 1130                  Nigeria    Africa 1957  37.802  37173340  1100.5926
## 1131                  Nigeria    Africa 1962  39.360  41871351  1150.9275
## 1132                  Nigeria    Africa 1967  41.040  47287752  1014.5141
## 1133                  Nigeria    Africa 1972  42.821  53740085  1698.3888
## 1134                  Nigeria    Africa 1977  44.514  62209173  1981.9518
## 1135                  Nigeria    Africa 1982  45.826  73039376  1576.9738
## 1136                  Nigeria    Africa 1987  46.886  81551520  1385.0296
## 1137                  Nigeria    Africa 1992  47.472  93364244  1619.8482
## 1138                  Nigeria    Africa 1997  47.464 106207839  1624.9413
## 1139                  Nigeria    Africa 2002  46.608 119901274  1615.2864
## 1140                  Nigeria    Africa 2007  46.859 135031164  2013.9773
## 1261                  Reunion    Africa 1952  52.724    257700  2718.8853
## 1262                  Reunion    Africa 1957  55.090    308700  2769.4518
## 1263                  Reunion    Africa 1962  57.666    358900  3173.7233
## 1264                  Reunion    Africa 1967  60.542    414024  4021.1757
## 1265                  Reunion    Africa 1972  64.274    461633  5047.6586
## 1266                  Reunion    Africa 1977  67.064    492095  4319.8041
## 1267                  Reunion    Africa 1982  69.885    517810  5267.2194
## 1268                  Reunion    Africa 1987  71.913    562035  5303.3775
## 1269                  Reunion    Africa 1992  73.615    622191  6101.2558
## 1270                  Reunion    Africa 1997  74.772    684810  6071.9414
## 1271                  Reunion    Africa 2002  75.744    743981  6316.1652
## 1272                  Reunion    Africa 2007  76.442    798094  7670.1226
## 1285                   Rwanda    Africa 1952  40.000   2534927   493.3239
## 1286                   Rwanda    Africa 1957  41.500   2822082   540.2894
## 1287                   Rwanda    Africa 1962  43.000   3051242   597.4731
## 1288                   Rwanda    Africa 1967  44.100   3451079   510.9637
## 1289                   Rwanda    Africa 1972  44.600   3992121   590.5807
## 1290                   Rwanda    Africa 1977  45.000   4657072   670.0806
## 1291                   Rwanda    Africa 1982  46.218   5507565   881.5706
## 1292                   Rwanda    Africa 1987  44.020   6349365   847.9912
## 1293                   Rwanda    Africa 1992  23.599   7290203   737.0686
## 1294                   Rwanda    Africa 1997  36.087   7212583   589.9445
## 1295                   Rwanda    Africa 2002  43.413   7852401   785.6538
## 1296                   Rwanda    Africa 2007  46.242   8860588   863.0885
## 1297    Sao Tome and Principe    Africa 1952  46.471     60011   879.5836
## 1298    Sao Tome and Principe    Africa 1957  48.945     61325   860.7369
## 1299    Sao Tome and Principe    Africa 1962  51.893     65345  1071.5511
## 1300    Sao Tome and Principe    Africa 1967  54.425     70787  1384.8406
## 1301    Sao Tome and Principe    Africa 1972  56.480     76595  1532.9853
## 1302    Sao Tome and Principe    Africa 1977  58.550     86796  1737.5617
## 1303    Sao Tome and Principe    Africa 1982  60.351     98593  1890.2181
## 1304    Sao Tome and Principe    Africa 1987  61.728    110812  1516.5255
## 1305    Sao Tome and Principe    Africa 1992  62.742    125911  1428.7778
## 1306    Sao Tome and Principe    Africa 1997  63.306    145608  1339.0760
## 1307    Sao Tome and Principe    Africa 2002  64.337    170372  1353.0924
## 1308    Sao Tome and Principe    Africa 2007  65.528    199579  1598.4351
## 1321                  Senegal    Africa 1952  37.278   2755589  1450.3570
## 1322                  Senegal    Africa 1957  39.329   3054547  1567.6530
## 1323                  Senegal    Africa 1962  41.454   3430243  1654.9887
## 1324                  Senegal    Africa 1967  43.563   3965841  1612.4046
## 1325                  Senegal    Africa 1972  45.815   4588696  1597.7121
## 1326                  Senegal    Africa 1977  48.879   5260855  1561.7691
## 1327                  Senegal    Africa 1982  52.379   6147783  1518.4800
## 1328                  Senegal    Africa 1987  55.769   7171347  1441.7207
## 1329                  Senegal    Africa 1992  58.196   8307920  1367.8994
## 1330                  Senegal    Africa 1997  60.187   9535314  1392.3683
## 1331                  Senegal    Africa 2002  61.600  10870037  1519.6353
## 1332                  Senegal    Africa 2007  63.062  12267493  1712.4721
## 1345             Sierra Leone    Africa 1952  30.331   2143249   879.7877
## 1346             Sierra Leone    Africa 1957  31.570   2295678  1004.4844
## 1347             Sierra Leone    Africa 1962  32.767   2467895  1116.6399
## 1348             Sierra Leone    Africa 1967  34.113   2662190  1206.0435
## 1349             Sierra Leone    Africa 1972  35.400   2879013  1353.7598
## 1350             Sierra Leone    Africa 1977  36.788   3140897  1348.2852
## 1351             Sierra Leone    Africa 1982  38.445   3464522  1465.0108
## 1352             Sierra Leone    Africa 1987  40.006   3868905  1294.4478
## 1353             Sierra Leone    Africa 1992  38.333   4260884  1068.6963
## 1354             Sierra Leone    Africa 1997  39.897   4578212   574.6482
## 1355             Sierra Leone    Africa 2002  41.012   5359092   699.4897
## 1356             Sierra Leone    Africa 2007  42.568   6144562   862.5408
## 1393                  Somalia    Africa 1952  32.978   2526994  1135.7498
## 1394                  Somalia    Africa 1957  34.977   2780415  1258.1474
## 1395                  Somalia    Africa 1962  36.981   3080153  1369.4883
## 1396                  Somalia    Africa 1967  38.977   3428839  1284.7332
## 1397                  Somalia    Africa 1972  40.973   3840161  1254.5761
## 1398                  Somalia    Africa 1977  41.974   4353666  1450.9925
## 1399                  Somalia    Africa 1982  42.955   5828892  1176.8070
## 1400                  Somalia    Africa 1987  44.501   6921858  1093.2450
## 1401                  Somalia    Africa 1992  39.658   6099799   926.9603
## 1402                  Somalia    Africa 1997  43.795   6633514   930.5964
## 1403                  Somalia    Africa 2002  45.936   7753310   882.0818
## 1404                  Somalia    Africa 2007  48.159   9118773   926.1411
## 1405             South Africa    Africa 1952  45.009  14264935  4725.2955
## 1406             South Africa    Africa 1957  47.985  16151549  5487.1042
## 1407             South Africa    Africa 1962  49.951  18356657  5768.7297
## 1408             South Africa    Africa 1967  51.927  20997321  7114.4780
## 1409             South Africa    Africa 1972  53.696  23935810  7765.9626
## 1410             South Africa    Africa 1977  55.527  27129932  8028.6514
## 1411             South Africa    Africa 1982  58.161  31140029  8568.2662
## 1412             South Africa    Africa 1987  60.834  35933379  7825.8234
## 1413             South Africa    Africa 1992  61.888  39964159  7225.0693
## 1414             South Africa    Africa 1997  60.236  42835005  7479.1882
## 1415             South Africa    Africa 2002  53.365  44433622  7710.9464
## 1416             South Africa    Africa 2007  49.339  43997828  9269.6578
## 1441                    Sudan    Africa 1952  38.635   8504667  1615.9911
## 1442                    Sudan    Africa 1957  39.624   9753392  1770.3371
## 1443                    Sudan    Africa 1962  40.870  11183227  1959.5938
## 1444                    Sudan    Africa 1967  42.858  12716129  1687.9976
## 1445                    Sudan    Africa 1972  45.083  14597019  1659.6528
## 1446                    Sudan    Africa 1977  47.800  17104986  2202.9884
## 1447                    Sudan    Africa 1982  50.338  20367053  1895.5441
## 1448                    Sudan    Africa 1987  51.744  24725960  1507.8192
## 1449                    Sudan    Africa 1992  53.556  28227588  1492.1970
## 1450                    Sudan    Africa 1997  55.373  32160729  1632.2108
## 1451                    Sudan    Africa 2002  56.369  37090298  1993.3983
## 1452                    Sudan    Africa 2007  58.556  42292929  2602.3950
## 1453                Swaziland    Africa 1952  41.407    290243  1148.3766
## 1454                Swaziland    Africa 1957  43.424    326741  1244.7084
## 1455                Swaziland    Africa 1962  44.992    370006  1856.1821
## 1456                Swaziland    Africa 1967  46.633    420690  2613.1017
## 1457                Swaziland    Africa 1972  49.552    480105  3364.8366
## 1458                Swaziland    Africa 1977  52.537    551425  3781.4106
## 1459                Swaziland    Africa 1982  55.561    649901  3895.3840
## 1460                Swaziland    Africa 1987  57.678    779348  3984.8398
## 1461                Swaziland    Africa 1992  58.474    962344  3553.0224
## 1462                Swaziland    Africa 1997  54.289   1054486  3876.7685
## 1463                Swaziland    Africa 2002  43.869   1130269  4128.1169
## 1464                Swaziland    Africa 2007  39.613   1133066  4513.4806
## 1513                 Tanzania    Africa 1952  41.215   8322925   716.6501
## 1514                 Tanzania    Africa 1957  42.974   9452826   698.5356
## 1515                 Tanzania    Africa 1962  44.246  10863958   722.0038
## 1516                 Tanzania    Africa 1967  45.757  12607312   848.2187
## 1517                 Tanzania    Africa 1972  47.620  14706593   915.9851
## 1518                 Tanzania    Africa 1977  49.919  17129565   962.4923
## 1519                 Tanzania    Africa 1982  50.608  19844382   874.2426
## 1520                 Tanzania    Africa 1987  51.535  23040630   831.8221
## 1521                 Tanzania    Africa 1992  50.440  26605473   825.6825
## 1522                 Tanzania    Africa 1997  48.466  30686889   789.1862
## 1523                 Tanzania    Africa 2002  49.651  34593779   899.0742
## 1524                 Tanzania    Africa 2007  52.517  38139640  1107.4822
## 1537                     Togo    Africa 1952  38.596   1219113   859.8087
## 1538                     Togo    Africa 1957  41.208   1357445   925.9083
## 1539                     Togo    Africa 1962  43.922   1528098  1067.5348
## 1540                     Togo    Africa 1967  46.769   1735550  1477.5968
## 1541                     Togo    Africa 1972  49.759   2056351  1649.6602
## 1542                     Togo    Africa 1977  52.887   2308582  1532.7770
## 1543                     Togo    Africa 1982  55.471   2644765  1344.5780
## 1544                     Togo    Africa 1987  56.941   3154264  1202.2014
## 1545                     Togo    Africa 1992  58.061   3747553  1034.2989
## 1546                     Togo    Africa 1997  58.390   4320890   982.2869
## 1547                     Togo    Africa 2002  57.561   4977378   886.2206
## 1548                     Togo    Africa 2007  58.420   5701579   882.9699
## 1561                  Tunisia    Africa 1952  44.600   3647735  1468.4756
## 1562                  Tunisia    Africa 1957  47.100   3950849  1395.2325
## 1563                  Tunisia    Africa 1962  49.579   4286552  1660.3032
## 1564                  Tunisia    Africa 1967  52.053   4786986  1932.3602
## 1565                  Tunisia    Africa 1972  55.602   5303507  2753.2860
## 1566                  Tunisia    Africa 1977  59.837   6005061  3120.8768
## 1567                  Tunisia    Africa 1982  64.048   6734098  3560.2332
## 1568                  Tunisia    Africa 1987  66.894   7724976  3810.4193
## 1569                  Tunisia    Africa 1992  70.001   8523077  4332.7202
## 1570                  Tunisia    Africa 1997  71.973   9231669  4876.7986
## 1571                  Tunisia    Africa 2002  73.042   9770575  5722.8957
## 1572                  Tunisia    Africa 2007  73.923  10276158  7092.9230
## 1585                   Uganda    Africa 1952  39.978   5824797   734.7535
## 1586                   Uganda    Africa 1957  42.571   6675501   774.3711
## 1587                   Uganda    Africa 1962  45.344   7688797   767.2717
## 1588                   Uganda    Africa 1967  48.051   8900294   908.9185
## 1589                   Uganda    Africa 1972  51.016  10190285   950.7359
## 1590                   Uganda    Africa 1977  50.350  11457758   843.7331
## 1591                   Uganda    Africa 1982  49.849  12939400   682.2662
## 1592                   Uganda    Africa 1987  51.509  15283050   617.7244
## 1593                   Uganda    Africa 1992  48.825  18252190   644.1708
## 1594                   Uganda    Africa 1997  44.578  21210254   816.5591
## 1595                   Uganda    Africa 2002  47.813  24739869   927.7210
## 1596                   Uganda    Africa 2007  51.542  29170398  1056.3801
## 1681                   Zambia    Africa 1952  42.038   2672000  1147.3888
## 1682                   Zambia    Africa 1957  44.077   3016000  1311.9568
## 1683                   Zambia    Africa 1962  46.023   3421000  1452.7258
## 1684                   Zambia    Africa 1967  47.768   3900000  1777.0773
## 1685                   Zambia    Africa 1972  50.107   4506497  1773.4983
## 1686                   Zambia    Africa 1977  51.386   5216550  1588.6883
## 1687                   Zambia    Africa 1982  51.821   6100407  1408.6786
## 1688                   Zambia    Africa 1987  50.821   7272406  1213.3151
## 1689                   Zambia    Africa 1992  46.100   8381163  1210.8846
## 1690                   Zambia    Africa 1997  40.238   9417789  1071.3538
## 1691                   Zambia    Africa 2002  39.193  10595811  1071.6139
## 1692                   Zambia    Africa 2007  42.384  11746035  1271.2116
## 1693                 Zimbabwe    Africa 1952  48.451   3080907   406.8841
## 1694                 Zimbabwe    Africa 1957  50.469   3646340   518.7643
## 1695                 Zimbabwe    Africa 1962  52.358   4277736   527.2722
## 1696                 Zimbabwe    Africa 1967  53.995   4995432   569.7951
## 1697                 Zimbabwe    Africa 1972  55.635   5861135   799.3622
## 1698                 Zimbabwe    Africa 1977  57.674   6642107   685.5877
## 1699                 Zimbabwe    Africa 1982  60.363   7636524   788.8550
## 1700                 Zimbabwe    Africa 1987  62.351   9216418   706.1573
## 1701                 Zimbabwe    Africa 1992  60.377  10704340   693.4208
## 1702                 Zimbabwe    Africa 1997  46.809  11404948   792.4500
## 1703                 Zimbabwe    Africa 2002  39.989  11926563   672.0386
## 1704                 Zimbabwe    Africa 2007  43.487  12311143   469.7093
```

---
## data.frame - indexing

- A new object can be created from the results of indexing


```r
year_2007 &lt;- gapminder[gapminder$year==2007, ]
year_2007
```

```
##                       country continent year lifeExp        pop  gdpPercap
## 12                Afghanistan      Asia 2007  43.828   31889923   974.5803
## 24                    Albania    Europe 2007  76.423    3600523  5937.0295
## 36                    Algeria    Africa 2007  72.301   33333216  6223.3675
## 48                     Angola    Africa 2007  42.731   12420476  4797.2313
## 60                  Argentina  Americas 2007  75.320   40301927 12779.3796
## 72                  Australia   Oceania 2007  81.235   20434176 34435.3674
## 84                    Austria    Europe 2007  79.829    8199783 36126.4927
## 96                    Bahrain      Asia 2007  75.635     708573 29796.0483
## 108                Bangladesh      Asia 2007  64.062  150448339  1391.2538
## 120                   Belgium    Europe 2007  79.441   10392226 33692.6051
## 132                     Benin    Africa 2007  56.728    8078314  1441.2849
## 144                   Bolivia  Americas 2007  65.554    9119152  3822.1371
## 156    Bosnia and Herzegovina    Europe 2007  74.852    4552198  7446.2988
## 168                  Botswana    Africa 2007  50.728    1639131 12569.8518
## 180                    Brazil  Americas 2007  72.390  190010647  9065.8008
## 192                  Bulgaria    Europe 2007  73.005    7322858 10680.7928
## 204              Burkina Faso    Africa 2007  52.295   14326203  1217.0330
## 216                   Burundi    Africa 2007  49.580    8390505   430.0707
## 228                  Cambodia      Asia 2007  59.723   14131858  1713.7787
## 240                  Cameroon    Africa 2007  50.430   17696293  2042.0952
## 252                    Canada  Americas 2007  80.653   33390141 36319.2350
## 264  Central African Republic    Africa 2007  44.741    4369038   706.0165
## 276                      Chad    Africa 2007  50.651   10238807  1704.0637
## 288                     Chile  Americas 2007  78.553   16284741 13171.6388
## 300                     China      Asia 2007  72.961 1318683096  4959.1149
## 312                  Colombia  Americas 2007  72.889   44227550  7006.5804
## 324                   Comoros    Africa 2007  65.152     710960   986.1479
## 336          Congo, Dem. Rep.    Africa 2007  46.462   64606759   277.5519
## 348               Congo, Rep.    Africa 2007  55.322    3800610  3632.5578
## 360                Costa Rica  Americas 2007  78.782    4133884  9645.0614
## 372             Cote d'Ivoire    Africa 2007  48.328   18013409  1544.7501
## 384                   Croatia    Europe 2007  75.748    4493312 14619.2227
## 396                      Cuba  Americas 2007  78.273   11416987  8948.1029
## 408            Czech Republic    Europe 2007  76.486   10228744 22833.3085
## 420                   Denmark    Europe 2007  78.332    5468120 35278.4187
## 432                  Djibouti    Africa 2007  54.791     496374  2082.4816
## 444        Dominican Republic  Americas 2007  72.235    9319622  6025.3748
## 456                   Ecuador  Americas 2007  74.994   13755680  6873.2623
## 468                     Egypt    Africa 2007  71.338   80264543  5581.1810
## 480               El Salvador  Americas 2007  71.878    6939688  5728.3535
## 492         Equatorial Guinea    Africa 2007  51.579     551201 12154.0897
## 504                   Eritrea    Africa 2007  58.040    4906585   641.3695
## 516                  Ethiopia    Africa 2007  52.947   76511887   690.8056
## 528                   Finland    Europe 2007  79.313    5238460 33207.0844
## 540                    France    Europe 2007  80.657   61083916 30470.0167
## 552                     Gabon    Africa 2007  56.735    1454867 13206.4845
## 564                    Gambia    Africa 2007  59.448    1688359   752.7497
## 576                   Germany    Europe 2007  79.406   82400996 32170.3744
## 588                     Ghana    Africa 2007  60.022   22873338  1327.6089
## 600                    Greece    Europe 2007  79.483   10706290 27538.4119
## 612                 Guatemala  Americas 2007  70.259   12572928  5186.0500
## 624                    Guinea    Africa 2007  56.007    9947814   942.6542
## 636             Guinea-Bissau    Africa 2007  46.388    1472041   579.2317
## 648                     Haiti  Americas 2007  60.916    8502814  1201.6372
## 660                  Honduras  Americas 2007  70.198    7483763  3548.3308
## 672          Hong Kong, China      Asia 2007  82.208    6980412 39724.9787
## 684                   Hungary    Europe 2007  73.338    9956108 18008.9444
## 696                   Iceland    Europe 2007  81.757     301931 36180.7892
## 708                     India      Asia 2007  64.698 1110396331  2452.2104
## 720                 Indonesia      Asia 2007  70.650  223547000  3540.6516
## 732                      Iran      Asia 2007  70.964   69453570 11605.7145
## 744                      Iraq      Asia 2007  59.545   27499638  4471.0619
## 756                   Ireland    Europe 2007  78.885    4109086 40675.9964
## 768                    Israel      Asia 2007  80.745    6426679 25523.2771
## 780                     Italy    Europe 2007  80.546   58147733 28569.7197
## 792                   Jamaica  Americas 2007  72.567    2780132  7320.8803
## 804                     Japan      Asia 2007  82.603  127467972 31656.0681
## 816                    Jordan      Asia 2007  72.535    6053193  4519.4612
## 828                     Kenya    Africa 2007  54.110   35610177  1463.2493
## 840          Korea, Dem. Rep.      Asia 2007  67.297   23301725  1593.0655
## 852               Korea, Rep.      Asia 2007  78.623   49044790 23348.1397
## 864                    Kuwait      Asia 2007  77.588    2505559 47306.9898
## 876                   Lebanon      Asia 2007  71.993    3921278 10461.0587
## 888                   Lesotho    Africa 2007  42.592    2012649  1569.3314
## 900                   Liberia    Africa 2007  45.678    3193942   414.5073
## 912                     Libya    Africa 2007  73.952    6036914 12057.4993
## 924                Madagascar    Africa 2007  59.443   19167654  1044.7701
## 936                    Malawi    Africa 2007  48.303   13327079   759.3499
## 948                  Malaysia      Asia 2007  74.241   24821286 12451.6558
## 960                      Mali    Africa 2007  54.467   12031795  1042.5816
## 972                Mauritania    Africa 2007  64.164    3270065  1803.1515
## 984                 Mauritius    Africa 2007  72.801    1250882 10956.9911
## 996                    Mexico  Americas 2007  76.195  108700891 11977.5750
## 1008                 Mongolia      Asia 2007  66.803    2874127  3095.7723
## 1020               Montenegro    Europe 2007  74.543     684736  9253.8961
## 1032                  Morocco    Africa 2007  71.164   33757175  3820.1752
## 1044               Mozambique    Africa 2007  42.082   19951656   823.6856
## 1056                  Myanmar      Asia 2007  62.069   47761980   944.0000
## 1068                  Namibia    Africa 2007  52.906    2055080  4811.0604
## 1080                    Nepal      Asia 2007  63.785   28901790  1091.3598
## 1092              Netherlands    Europe 2007  79.762   16570613 36797.9333
## 1104              New Zealand   Oceania 2007  80.204    4115771 25185.0091
## 1116                Nicaragua  Americas 2007  72.899    5675356  2749.3210
## 1128                    Niger    Africa 2007  56.867   12894865   619.6769
## 1140                  Nigeria    Africa 2007  46.859  135031164  2013.9773
## 1152                   Norway    Europe 2007  80.196    4627926 49357.1902
## 1164                     Oman      Asia 2007  75.640    3204897 22316.1929
## 1176                 Pakistan      Asia 2007  65.483  169270617  2605.9476
## 1188                   Panama  Americas 2007  75.537    3242173  9809.1856
## 1200                 Paraguay  Americas 2007  71.752    6667147  4172.8385
## 1212                     Peru  Americas 2007  71.421   28674757  7408.9056
## 1224              Philippines      Asia 2007  71.688   91077287  3190.4810
## 1236                   Poland    Europe 2007  75.563   38518241 15389.9247
## 1248                 Portugal    Europe 2007  78.098   10642836 20509.6478
## 1260              Puerto Rico  Americas 2007  78.746    3942491 19328.7090
## 1272                  Reunion    Africa 2007  76.442     798094  7670.1226
## 1284                  Romania    Europe 2007  72.476   22276056 10808.4756
## 1296                   Rwanda    Africa 2007  46.242    8860588   863.0885
## 1308    Sao Tome and Principe    Africa 2007  65.528     199579  1598.4351
## 1320             Saudi Arabia      Asia 2007  72.777   27601038 21654.8319
## 1332                  Senegal    Africa 2007  63.062   12267493  1712.4721
## 1344                   Serbia    Europe 2007  74.002   10150265  9786.5347
## 1356             Sierra Leone    Africa 2007  42.568    6144562   862.5408
## 1368                Singapore      Asia 2007  79.972    4553009 47143.1796
## 1380          Slovak Republic    Europe 2007  74.663    5447502 18678.3144
## 1392                 Slovenia    Europe 2007  77.926    2009245 25768.2576
## 1404                  Somalia    Africa 2007  48.159    9118773   926.1411
## 1416             South Africa    Africa 2007  49.339   43997828  9269.6578
## 1428                    Spain    Europe 2007  80.941   40448191 28821.0637
## 1440                Sri Lanka      Asia 2007  72.396   20378239  3970.0954
## 1452                    Sudan    Africa 2007  58.556   42292929  2602.3950
## 1464                Swaziland    Africa 2007  39.613    1133066  4513.4806
## 1476                   Sweden    Europe 2007  80.884    9031088 33859.7484
## 1488              Switzerland    Europe 2007  81.701    7554661 37506.4191
## 1500                    Syria      Asia 2007  74.143   19314747  4184.5481
## 1512                   Taiwan      Asia 2007  78.400   23174294 28718.2768
## 1524                 Tanzania    Africa 2007  52.517   38139640  1107.4822
## 1536                 Thailand      Asia 2007  70.616   65068149  7458.3963
## 1548                     Togo    Africa 2007  58.420    5701579   882.9699
## 1560      Trinidad and Tobago  Americas 2007  69.819    1056608 18008.5092
## 1572                  Tunisia    Africa 2007  73.923   10276158  7092.9230
## 1584                   Turkey    Europe 2007  71.777   71158647  8458.2764
## 1596                   Uganda    Africa 2007  51.542   29170398  1056.3801
## 1608           United Kingdom    Europe 2007  79.425   60776238 33203.2613
## 1620            United States  Americas 2007  78.242  301139947 42951.6531
## 1632                  Uruguay  Americas 2007  76.384    3447496 10611.4630
## 1644                Venezuela  Americas 2007  73.747   26084662 11415.8057
## 1656                  Vietnam      Asia 2007  74.249   85262356  2441.5764
## 1668       West Bank and Gaza      Asia 2007  73.422    4018332  3025.3498
## 1680              Yemen, Rep.      Asia 2007  62.698   22211743  2280.7699
## 1692                   Zambia    Africa 2007  42.384   11746035  1271.2116
## 1704                 Zimbabwe    Africa 2007  43.487   12311143   469.7093
```

---
## data.frame - indexing

- object[row,column]

```r
gapminder[2, 1]
gapminder[1, 3]
gapminder[, 1]
gapminder[1]
gapminder[1, ]
gapminder[0, 3]
gapminder[-2, ]
gapminder[, -1]
gapminder[c(1,5,7), ]
gapminder[, c(1,2)]
gapminder[gapminder$pop&lt;100000, ]
gapminder[gapminder$year==1952, c(4)]
```

---
## data.frame - indexing


```r
gapminder$lifeExp
```


```
## [1] 28.801 30.332 31.997 34.020 36.088 38.438
```


```r
gapminder$continent
```


```
## [1] Asia Asia Asia Asia Asia Asia
## Levels: Africa Americas Asia Europe Oceania
```
---
## **dplyr**


```r
# install.packages('dplyr')
# devtools::install_github("tidyverse/dplyr")
library('dplyr')
```

- **dplyr** is a package for data exploration and transformation
- Basic functions of the **dplyr** package are `select()`, `arrange()`, `filter()`, `mutate()`, and `summarize()`
- Another important function is `group_by()`
- Additionally, **dplyr** package implements a pipe operator (`%&gt;%`), joins and set operations, and moving window operations

---
## **dplyr** - `select()`

- `select()` function picks columns by its name
- Many additional features - `?dplyr::select()`

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28.801 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 779.4453 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.332 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 820.8530 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1962 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 31.997 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10267083 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 853.1007 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1967 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 34.020 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11537966 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 836.1971 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1972 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 36.088 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 13079460 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 739.9811 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1977 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 38.438 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 14880372 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 786.1134 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `select()`


```r
gapminder_sel1 &lt;- select(gapminder, country, year, pop)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;


```r
gapminder_sel2 &lt;- select(gapminder, -continent)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28.801 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 779.4453 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.332 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 820.8530 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `arrange()`

- `arrange()` reorder rows in ascending order...


```r
gapminder_arr1 &lt;- arrange(gapminder, lifeExp)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Rwanda &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1992 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 23.599 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7290203 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 737.0686 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28.801 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 779.4453 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Gambia &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.000 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 284320 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 485.2307 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Angola &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.015 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 4232095 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 3520.6103 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Sierra Leone &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.331 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2143249 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 879.7877 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `arrange()`

- ...or descending order


```r
gapminder_arr1 &lt;- arrange(gapminder, desc(lifeExp))
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Japan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 82.603 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 127467972 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 31656.07 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Hong Kong, China &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 82.208 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 6980412 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 39724.98 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Japan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2002 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 82.000 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 127065841 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28604.59 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Iceland &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Europe &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 81.757 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 301931 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 36180.79 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Switzerland &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Europe &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 81.701 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7554661 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 37506.42 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `filter()`

- `filter()` keeps rows matching given criteria
- Logical operators, such as `==, !=, &gt;, &gt;=, &lt;, &lt;=, &amp;, |` can be used


```r
gapminder_fil1 &lt;- filter(gapminder, year == 2007)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 43.828 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 31889923 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 974.5803 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Albania &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Europe &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 76.423 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 3600523 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 5937.0295 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `filter()`


```r
gapminder_fil2 &lt;- filter(gapminder, year == 2007 &amp; pop &lt;= 999999)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Bahrain &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 75.635 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 708573 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 29796.0483 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Comoros &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 65.152 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 710960 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 986.1479 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;


```r
gapminder_fil2 &lt;- filter(gapminder, continent != 'Asia' |  lifeExp &lt; 30)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28.801 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 779.4453 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Albania &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Europe &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 55.230 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1282697 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1601.0561 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `mutate()`

- `mutate()` function creates new variables based on existing variables


```r
gapminder_mut1 &lt;- mutate(gapminder, gdp_mil = (gdpPercap * pop) / 1000000)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; lifeExp &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdpPercap &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; gdp_mil &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 28.801 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 779.4453 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 6567.086 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 30.332 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 820.8530 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7585.449 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1962 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 31.997 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10267083 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 853.1007 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8758.856 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1967 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 34.020 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11537966 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 836.1971 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9648.014 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1972 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 36.088 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 13079460 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 739.9811 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9678.553 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **dplyr** - `summarize()`

- `summarize()` function can be used to reduce variables to values


```r
gapminder_sum1 &lt;- summarize(gapminder, mean_le = mean(lifeExp))
```


```
##    mean_le
## 1 59.47444
```


```r
gapminder_sum2 &lt;- summarize(gapminder, 
                            mean_le = mean(lifeExp), 
                            min_le = min(lifeExp), 
                            max_le = max(lifeExp))
```


```
##    mean_le min_le max_le
## 1 59.47444 23.599 82.603
```

---
## **dplyr** - `group_by()`

- `group_by()` does not change data. Its role is to create the groups of variables to be used by the previous functions


```r
gapminder2007 &lt;- filter(gapminder, year == 2007)
gapminder_grp1 &lt;- group_by(gapminder2007, continent)
```


```
## Source: local data frame [6 x 6]
## Groups: continent [5]
## 
##       country continent  year lifeExp      pop  gdpPercap
##        &lt;fctr&gt;    &lt;fctr&gt; &lt;int&gt;   &lt;dbl&gt;    &lt;dbl&gt;      &lt;dbl&gt;
## 1 Afghanistan      Asia  2007  43.828 31889923   974.5803
## 2     Albania    Europe  2007  76.423  3600523  5937.0295
## 3     Algeria    Africa  2007  72.301 33333216  6223.3675
## 4      Angola    Africa  2007  42.731 12420476  4797.2313
## 5   Argentina  Americas  2007  75.320 40301927 12779.3796
## 6   Australia   Oceania  2007  81.235 20434176 34435.3674
```

---
## **dplyr** - `group_by()`


```r
gapminder_grp1 &lt;- summarize(gapminder_grp1, mean_lifeExp = mean(lifeExp))
```


&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; mean_lifeExp &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 54.80604 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Americas &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 73.60812 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Asia &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 70.72848 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Europe &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 77.64860 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Oceania &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 80.71950 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **tidyr**


```r
# install.packages('tidyr')
library('tidyr')
```

- Many of real world datasets are messy - they are not organized in a way we (or R functions) expect. It is important to use "tidy data" framework to ease the manipulation, modeling, and visualisation of datasets. In "tidy data":
    - Each variable forms a column
    - Each observation forms a row
    - Each type of observational unit forms a table (data frame)
- There are two data formats in "tidy data" - wide format and long format 
- More information about "tidy data" can be found here - http://vita.had.co.nz/papers/tidy-data.html
- The **tidyr** package has two main functions - `gather()` and `spread()`, and several additional functions

---
## **tidyr** - `spread()`

- `spread()` takes two columns (key &amp; value) and spreads them into multiple columns (creates data in a "wide" format)


```r
gapminder_sel &lt;- select(gapminder, -continent, -lifeExp, -gdpPercap)
gapminder_spread &lt;- spread(gapminder_sel, country, pop)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Afghanistan &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Albania &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Algeria &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Angola &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Argentina &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Australia &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Austria &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Bahrain &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; Bangladesh &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1282697 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9279525 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 4232095 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 17876956 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8691212 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 6927772 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 120447 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 46886859 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1476505 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10270856 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 4561361 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 19610538 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9712569 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 6965860 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 138655 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 51365468 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1962 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10267083 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1728137 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11000948 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 4826015 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 21283783 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10794968 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7129864 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 171863 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 56839289 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1967 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11537966 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 1984060 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 12760499 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 5247469 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 22934225 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11872264 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7376998 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 202182 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 62821884 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1972 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 13079460 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 2263554 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 14760787 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 5894858 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 24779799 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 13177000 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7544201 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 230800 &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 70759295 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## **tidyr** - `gather()`

- `gather()` reshapes data from a wide format to a long format


```r
gapminder_gather &lt;- gather(gapminder_spread, country, pop, -year)
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:right;"&gt; year &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1952 &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 8425333 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1957 &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9240934 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1962 &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10267083 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1967 &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11537966 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:right;"&gt; 1972 &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Afghanistan &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 13079460 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## `%&gt;%` operator

The usual approach to perform numerous operations in R is either:

- by creating many "subobjects":


```r
gapminder_sel &lt;- select(gapminder, country, continent, pop)
gapminder_africa &lt;- filter(gapminder_sel, continent=='Africa')
```

- ...or by nesting:


```r
gapminder_africa &lt;- filter(select(gapminder, country, continent, pop), continent=='Africa')
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9279525 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10270856 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11000948 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 12760499 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 14760787 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## `%&gt;%` operator

- Nowadays, it could be easier done with the use of the `%&gt;%` ("pipe") operator (**magrittr** or **dplyr** package)
- In this approach, commands are written in a (more) natural order


```r
gapminder_africa &lt;- gapminder %&gt;% 
        select(country, continent, pop) %&gt;% 
        filter(continent=='Africa')
```

&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; continent &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; pop &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 9279525 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10270856 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 11000948 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 12760499 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Algeria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; Africa &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 14760787 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## `%&gt;%` operator


```r
gapminder_proc &lt;- gapminder %&gt;% 
        filter(continent=='Europe', year==2007) %&gt;% 
        mutate(pop_in_thousands=pop/1000) %&gt;% 
        select(country, gdpPercap, pop_in_thousands) %&gt;% 
        gather(key, value, gdpPercap, pop_in_thousands)
```


&lt;table&gt;
 &lt;thead&gt;
  &lt;tr&gt;
   &lt;th style="text-align:left;"&gt; country &lt;/th&gt;
   &lt;th style="text-align:left;"&gt; key &lt;/th&gt;
   &lt;th style="text-align:right;"&gt; value &lt;/th&gt;
  &lt;/tr&gt;
 &lt;/thead&gt;
&lt;tbody&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Albania &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; gdpPercap &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 5937.030 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Austria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; gdpPercap &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 36126.493 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Belgium &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; gdpPercap &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 33692.605 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Bosnia and Herzegovina &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; gdpPercap &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 7446.299 &lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
   &lt;td style="text-align:left;"&gt; Bulgaria &lt;/td&gt;
   &lt;td style="text-align:left;"&gt; gdpPercap &lt;/td&gt;
   &lt;td style="text-align:right;"&gt; 10680.793 &lt;/td&gt;
  &lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;

---
## Resources

- [R for Data Science](http://r4ds.had.co.nz/) - a great book which contains chapters for beginners and for more advanced users
- [Tidy data](https://cran.r-project.org/web/packages/tidyr/vignettes/tidy-data.html) - an overview of a "tidy data" approach
- [dplyr](http://dplyr.tidyverse.org/) - an official website of the `dplyr` package
- [tidyr](http://tidyr.tidyverse.org/) - an official website of the `tidyr` package
- [Introduction to dplyr](http://stat545.com/block009_dplyr-intro.html) - a clear introdution to the `dplyr` package
- [Tidy data lesson using Lord of the Rings data](https://github.com/jennybc/lotr-tidy#readme) - an introduction to a "tidy data" and the `tidyr` package using Lord of the Rings data
- [Data Wrangling with dplyr and tidyr Cheat Sheet](https://www.rstudio.com/wp-content/uploads/2015/02/data-wrangling-cheatsheet.pdf) - a two-pages summary of `dplyr` and `tidyr` functions
- [Cheatsheet for dplyr join functions](http://stat545.com/bit001_dplyr-cheatsheet.html) - examples of `dplyr` join functions
- [A new data processing workflow for R: dplyr, magrittr, tidyr, ggplot2](http://zevross.com/blog/2015/01/13/a-new-data-processing-workflow-for-r-dplyr-magrittr-tidyr-ggplot2/) - a data processing workflow example
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