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fetch-simple-geojson-p

This module fetches a geojson file from an http link and reduces the file size before implementation.

fetch-simple-geojson-p reduces the file size by:

  • Removing unnecessary digits via turf.truncate
  • Simplifying geometry via turf.simplify()
  • Keeping only specified property values

This module is promisified; a version for callbacks can be found under fetch-simple-geojson.

Installation

$ npm install fetch-simple-geojson-p -S

Usage

Require the module in the file where you'll be simplifying and run as a function simplify.

const fs = require('fsp')
const simplify = require('fetch-simple-geojson-p')

const data = 'https://opendata.arcgis.com/datasets/cd78700c5c5c4a338090ce4c7b996f03_3.geojson'
const options = {
  tolerance: 0.0001,
  highQuality: true,
  keepProperties: ['NAME']
}

simplify(data, options)
  .then(result => {
    console.log('File Successfully Written.');
    return fsp.writeFile('output.json', JSON.stringify(result));
  });

Data Formats

This module only take input data that is in geoJSON format - not regular json, ndjson or topogeojson. Many geoJSON data sets can be found on opendata.arcgis.com or opendata.gov.

Available Options

  • tolerance: [number] Simplification tolerance (optional, default 1)
  • highQuality: [boolean] Whether or not to spend more time to create a higher-quality simplification with a different algorithm (optional; default false)
  • keepProperties: [array[string, string, ...]] Discards superfluous properties on a geoJSON file, unless specifically mentioned.

The properties you may or may not want to keep will vary, depending on your geoJSON file, but usually consist of single-depth { key: value } mappings. Common properties include:

  • OBJECTID
  • NAME

Contribute

Accepting pull requests and issues! Click through to our GitHub repo to contribute or post an issue.