Convert GeoJSON coordinates to and from encoded polylines. Supports encoding or decoding geometries/coordinates for all 9 standard GeoJSON types. Use it in Node.js (optionally as a transform stream), in the browser, as a Web Worker, or from the command line.
npm install geojson-polylineConvert a GeoJSON object's coordinates to encoded polylines.
geoJSON: A GeoJSON object (required).options: An optional Object with the following possible properties:precision: A Number specifying the number of digits to keep for lat/lon. Default is5.
Aliases: polyline, polyLine, toEncoded, fromGeoJSON, toPolyline.
const encode = require('geojson-polyline').encode
const polygon = {
type: 'Polygon',
coordinates: [
[[-81.63829, 41.48093], [-81.63628, 41.47993], [-81.63625, 41.47931], [-81.63829, 41.48033], [-81.63829, 41.48093]]
]
}
const encoded = encode(polygon)
// => { type: 'Polygon', coordinates: ['yvd|Fh~gqNfEqKzBEkEvKwB?'] }Convert a polyline-encoded GeoJSON to standard GeoJSON coordinate arrays.
polyGeo: A GeoJSON object whose coordinates are expressed as polylines (required).options: An optional Object with the following possible properties:precision: A Number specifying the precision that the polyline was encoded with. Default is5.
Aliases: decode, geojson, geoJson, geoJSON, fromEncoded, toGeoJSON fromPolyline.
const decode = require('geojson-polyline').decode
const polygon = {
type: 'Polygon',
coordinates: ['yvd|Fh~gqNfEqKzBEkEvKwB?']
}
const geoJSON = decode(polygon)
// => { type: 'Polygon', coordinates: [[[-81.63829, 41.48093], [-81.63628, 41.47993], [-81.63625, 41.47931], [-81.63829, 41.48033], [-81.63829, 41.48093]]]}Use the streaming API if you have streams instead of objects. Outputs newline-separated JSON.
var encode = require('geojson-polyline/stream').encode
// var decode = require('geojson-polyline/stream').decode
fs.createReadStream('./tl_2016_33_place.geojson')
.pipe(encode({precision: 4}))
.pipe(process.stdout)Standalone builds are available in /dist for in-browser usage, which are ES3 compatible.
<script src="dist/geojson-polyline.min.js"></script>
<script>
var decoded = encoded.map(GeoJSONPolyline.decode);
</script>If you want to decode polylines using Web Workers, that is supported out of the box:
var worker = new Worker('dist/geojson-polyline.min.js')
var decoded = []
encoded.forEach(function(encoded){
worker.postMessage(['decode', encoded])
})
worker.onmessage = function(event) {
decoded.push(event.data)
if(decoded.length === encoded.length) {
// Done!
}
}Currently, decoding and encoding is faster in the browser without using Web Workers.
Convert GeoJSON objects, features, and feature collections from the command line. Works great for .geojson files from ogr2ogr or shp2json.
npm install --global geojson-polylineUsage:
geojson-polyline <command> (read from stdin)
geojson-polyline <command> -f <file> [<file2>] [...]
geojson-polyline <command> <input>
Convert the coordinates of a GeoJSON object to and from encoded polylines.
In all cases, input should be a valid JSON object or newline-separated JSON.
Command is one of:
encode
decode
geojson
geoJson
geoJSON
polyline
polyLine
toEncoded
fromEncoded
toGeoJSON
fromGeoJSON
toPolyline
fromPolyline
geojson-polyline encode -f tabblock2010_56_pophu.geojson | mongoimport -c tabblock2010Google's encoded polyline algorithm provides for very efficient encoding and storage of coordinate data. The @mapbox/polyline library from MapBox provides an implementation to encode/decode polylines, but only supports GeoJSON "LineString" features, not "Polygons" or "MultiLineStrings".
ISC