# geojson-precision-ts [日本語版 README](./README.ja.md) [![jsdelivr CDN](https://data.jsdelivr.com/v1/package/npm/geojson-precision-ts/badge)](https://www.jsdelivr.com/package/npm/geojson-precision-ts) [![NPM Downloads](https://img.shields.io/npm/dm/geojson-precision-ts.svg?style=flat)](https://www.npmjs.com/package/geojson-precision-ts) [![Open in unpkg](https://img.shields.io/badge/Open%20in-unpkg-blue)](https://uiwjs.github.io/npm-unpkg/#/pkg/geojson-precision-ts/file/README.md) [![npm version](https://img.shields.io/npm/v/geojson-precision-ts.svg)](https://www.npmjs.com/package/geojson-precision-ts) [![Open in Gitpod](https://shields.io/badge/Open%20in-Gitpod-green?logo=Gitpod)](https://gitpod.io/#https://github.com/logue/geojson-precision) [![Twitter Follow](https://img.shields.io/twitter/follow/logue256?style=plastic)](https://twitter.com/logue256) Remove meaningless precision from your GeoJSON. If your coordinates go out to 7+ digits, you are [probably misrepresenting your data](http://gis.stackexchange.com/a/8674/14196). Most scenarios in which GeoJSON is useful (i.e. web-related applications) do not require survey-grade precision, and a higher value is placed on a compact file size. Trimming the precision of coordinates can greatly reduce file size, while removing the appearance of fake high precision. This fork is rewritten in typescript. ## Installation ```sh pnpm install geojson-precision-ts ``` ## Usage ```js parse(*geojson*, *precision*, *extrasPrecision*, *options*); omit(*geojson*); ``` | Parameter | Type | Default | Description | | --------------- | ---------------- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | geojson | GeoJSON | undefined | `geojson` is a valid GeoJSON object, and can be of type `Point`, `LineString`, `Polygon`, `MultiPoint`, `MultiPolygon`, `MultiLineString`, `GeometryCollection`, `Feature`, or `FeatureCollection`. If you are unsure whether or not your GeoJSON object is valid, you can validate it using [Ajv](https://ajv.js.org/) with the [geojson-schema](https://www.npmjs.com/package/geojson-schema) package. | | precision | number | 6 | `precision` is a positive integer. If your specified `precision` value is greater than the precision of the input geometry, the output precision will be the same as the input. For example, if your input coordinates are `[10.0, 20.0]`, and you specify a `precision` of `5`, the output will be the same as the input. | | extrasPrecision | number | 2 | `extrasPrecision` is a positive integer. If your specified `extrasPrecision` value is greater than the precision of the input geometry, the output precision will be the same as the input. For example, if your input coordinates are `[10.0, 20.0]`, and you specify a `precision` of `5`, the output will be the same as the input. | | options | OptionsInterface | `options` are bellows: | Option | Type | Default | Description | | ---------------- | ------- | ------- | -------------------------------------- | | ignorePoint | boolean | false | Skip Point | | ignoreLineString | boolean | false | Skip LineString | | ignorePolygon | boolean | false | Skip Polygon | | removeDuplicates | boolean | false | Delete points at the same coordinates. | `omit()` is an alias for `parse(t, 0, 0, { removeDuplicates: true })`, a function that removes all decimal coordinates from GeoJSON. ### How do you choose tolerance? Tolerance corresponds to how much resolution you can spare. Higher the tolerance, lower is your geometry's resolution. Tolerance is specified in degrees. The above table applies here too. The table gives a general idea on what tolerance to use for your task. For example, if you can allow an error of 1.11km (for example while plotting a big city map) set your tolerance to 0.01. ```plain decimal places degrees distance ------- ------- -------- 0 1 111 km 1 0.1 11.1 km 2 0.01 1.11 km 3 0.001 111 m 4 0.0001 11.1 m 5 0.00001 1.11 m 6 0.000001 11.1 cm 7 0.0000001 1.11 cm 8 0.00000001 1.11 mm ``` ### Example #### `parse()` function ```js import { parse } from 'geojson-precision-ts'; const trimmed = parse( { type: 'Point', coordinates: [18.984375, 57.32652122521709], }, 3 ); ``` `trimmed` will now look like this: ```json { "type": "Point", "coordinates": [18.984, 57.326] } ``` #### `omit()` function This is useful when you want to pin a static image by specifying pixels. ```js import { parse } from 'geojson-precision-ts'; const omitted = omit({ type: 'Point', coordinates: [18.984375, 57.32652122521709], }); ``` `omiited` will now look like this: ```json { "type": "Point", "coordinates": [18, 57] } ``` ## CLI Geojson-precision can also be used via the command line when installed globally (using `-g`). ### Parameters #### precision (-p) A positive integer specifying coordinate precision #### extras precision (-e) A positive integer specifying extra coordinate precision for things like the z value when the coordinate is \[longitude, latitude, elevation\]. #### input An input GeoJSON file #### output An output GeoJSON file ### Example use ```sh geojson-precision -p 4 input.json output.json ``` ## Inspiration Concepts, ideas, etc borrowed to various degrees from: - [wellknown](https://github.com/mapbox/wellknown/pull/18) - [LilJSON](https://github.com/migurski/LilJSON) ## License MIT Original Version by jczaplew's [geojson-precision](https://github.com/jczaplew/geojson-precision). TypeScript version by [Logue](https://github.com/logue). - Stop mutation of original object feature by [frankrowe](https://github.com/frankrowe). - Skip each geometry type feature by [andrewharvey](https://github.com/andrewharvey). - Remove duplicate points feature by [matthewrj](https://github.com/matthewrj). ## 🎨 Crafted for Developers This library is built with a focus on **UI/UX excellence** and **modern developer experience**. Maintaining it involves constant testing and updates to ensure everything works seamlessly. If you appreciate the attention to detail in this project, a small sponsorship would go a long way in supporting my work across the Vue.js and Metaverse ecosystems. [![GitHub Sponsors](https://img.shields.io/github/sponsors/logue?label=Sponsor&logo=github&color=ea4aaa)](https://github.com/sponsors/logue)