# Vector
> Create a vector (i.e., a one-dimensional [ndarray][@stdlib/ndarray/ctor]).
## Usage
```javascript
var vector = require( '@stdlib/ndarray/vector/ctor' );
```
#### vector( \[dtype]\[, options] )
Returns a one-dimensional [ndarray][@stdlib/ndarray/ctor] having a specified [data type][@stdlib/ndarray/dtypes].
```javascript
var getDType = require( '@stdlib/ndarray/dtype' );
var numel = require( '@stdlib/ndarray/numel' );
var arr = vector();
// returns
var len = numel( arr );
// returns 0
var dt = getDType( arr );
// returns 'float64'
```
By default, the function returns an [ndarray][@stdlib/ndarray/ctor] having a [`float64`][@stdlib/ndarray/dtypes] data type. To specify an alternative [data type][@stdlib/ndarray/dtypes], provide a `dtype` argument.
```javascript
var getDType = require( '@stdlib/ndarray/dtype' );
var numel = require( '@stdlib/ndarray/numel' );
var arr = vector( 'int32' );
// returns
var len = numel( arr );
// returns 0
var dt = getDType( arr );
// returns 'int32'
```
The function accepts the following options:
- **order**: specifies whether an [ndarray][@stdlib/ndarray/ctor] is `'row-major'` (C-style) or `'column-major'` (Fortran-style). Default: `'row-major'`.
- **mode**: specifies how to handle indices which exceed array dimensions (see [`ndarray`][@stdlib/ndarray/ctor]). Default: `'throw'`.
- **readonly**: boolean indicating whether an array should be **read-only**. Default: `false`.
#### vector( length\[, dtype]\[, options] )
Returns a one-dimensional [ndarray][@stdlib/ndarray/ctor] having a specified `length`.
```javascript
var numel = require( '@stdlib/ndarray/numel' );
var arr1 = vector( 5 );
// returns
var len1 = numel( arr1 );
// returns 5
var arr2 = vector( 5, 'uint8' );
// returns
var len2 = numel( arr2 );
// returns 5
```
#### vector( obj\[, dtype]\[, options] )
Creates a one-dimensional [ndarray][@stdlib/ndarray/ctor] from an array-like object or iterable.
```javascript
var numel = require( '@stdlib/ndarray/numel' );
var arr1 = vector( [ 0.5, 0.5, 0.5 ] );
// returns
var len1 = numel( arr1 );
// returns 3
var arr2 = vector( [ 0.5, 0.5, 0.5 ], 'float32' );
// returns
var len2 = numel( arr2 );
// returns 3
```
#### vector( buffer\[, byteOffset\[, length]]\[, dtype]\[, options] )
Returns a one-dimensional [ndarray][@stdlib/ndarray/ctor] view of an [`ArrayBuffer`][@stdlib/array/buffer].
```javascript
var ArrayBuffer = require( '@stdlib/array/buffer' );
var getDType = require( '@stdlib/ndarray/dtype' );
var numel = require( '@stdlib/ndarray/numel' );
var buf = new ArrayBuffer( 32 );
var arr1 = vector( buf );
// returns
var len1 = numel( arr1 );
// returns 4
var dt1 = getDType( arr1 );
// returns 'float64'
var arr2 = vector( buf, 'float32' );
// returns
var len2 = numel( arr2 );
// returns 8
var dt2 = getDType( arr2 );
// returns 'float32'
var arr3 = vector( buf, 16 );
// returns
var len3 = numel( arr3 );
// returns 2
var dt3 = getDType( arr3 );
// returns 'float64'
var arr4 = vector( buf, 16, 'float32' );
// returns
var len4 = numel( arr4 );
// returns 4
var dt4 = getDType( arr4 );
// returns 'float32'
var arr5 = vector( buf, 16, 1 );
// returns
var len5 = numel( arr5 );
// returns 1
var dt5 = getDType( arr5 );
// returns 'float64'
var arr6 = vector( buf, 10, 4, 'int16' );
// returns
var len6 = numel( arr6 );
// returns 4
var dt6 = getDType( arr6 );
// returns 'int16'
```
#### vector.factory( dtype\[, options] )
Returns a function for creating a one-dimensional [ndarray][@stdlib/ndarray/ctor].
```javascript
var getDType = require( '@stdlib/ndarray/dtype' );
var numel = require( '@stdlib/ndarray/numel' );
var Float32Vector = vector.factory( 'float32' );
var arr = new Float32Vector( [ 1, 2, 3 ] );
// returns
var dt = getDType( arr );
// returns 'float32'
var len = numel( arr );
// returns 3
```
The function supports the following parameters:
- **dtype**: [data type][@stdlib/ndarray/dtypes].
- **options**: function options (_optional_).
The function accepts the following options:
- **order**: specifies whether the default memory layout for a returned [ndarray][@stdlib/ndarray/ctor] should be `'row-major'` (C-style) or `'column-major'` (Fortran-style). Default: `'row-major'`.
- **mode**: specifies the default behavior when handling indices which exceed array dimensions (see [`ndarray`][@stdlib/ndarray/ctor]). Default: `'throw'`.
- **readonly**: boolean indicating whether to return a **read-only** [ndarray][@stdlib/ndarray/ctor] by default. Default: `false`.
The function returned by the `factory` method supports the same arguments and options as `vector` above, except for the `dtype` argument, as the returned function always returns a one-dimensional [ndarray][@stdlib/ndarray/ctor] having the same [data type][@stdlib/ndarray/dtypes].
When providing options to the returned function, the provided option values override the defaults established during function creation.
## Examples
```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var cartesianProduct = require( '@stdlib/array/cartesian-product' );
var unzip = require( '@stdlib/utils/unzip' );
var dtypes = require( '@stdlib/ndarray/dtypes' );
var sum = require( '@stdlib/blas/ext/sum' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var vector = require( '@stdlib/ndarray/vector/ctor' );
// Create an array of random array lengths:
var lens = discreteUniform( 10, 5, 15, {
'dtype': 'int32'
});
// Resolve a list of supported ndarray integer-valued data types:
var dts = dtypes( 'integer_and_generic' );
// Create length-dtype pairs:
var pairs = cartesianProduct( lens, dts );
// Split the pairs into individual arguments:
var args = unzip( pairs );
// Define a callback to create a random vector and return the sum of all vector elements:
function clbk( len, dtype ) {
var x = vector( discreteUniform( len, 0, 100 ), dtype );
return sum( x ).get();
}
// Apply the callback and print the results:
logEachMap( 'len: %2d. dtype: %7s. sum: %d.', args[ 0 ], args[ 1 ], clbk );
```
[@stdlib/array/buffer]: https://www.npmjs.com/package/@stdlib/array-buffer
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor
[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray/tree/main/dtypes
[@stdlib/ndarray/vector/float64]: https://github.com/stdlib-js/ndarray/tree/main/vector/float64
[@stdlib/ndarray/vector/float32]: https://github.com/stdlib-js/ndarray/tree/main/vector/float32
[@stdlib/ndarray/vector/complex128]: https://github.com/stdlib-js/ndarray/tree/main/vector/complex128
[@stdlib/ndarray/vector/complex64]: https://github.com/stdlib-js/ndarray/tree/main/vector/complex64