gopherj/polyline

polyline encoding and decoding in javascript

polyline

A simple google-esque polyline implementation in Javascript. Compatible with nodejs (npm install @mapbox/polyline and the browser (copy src/polyline.js)).

Encodes/decodes into [lat, lng] coordinate pairs. Use fromGeoJSON() to encode from GeoJSON objects, or toGeoJSON to decode to a GeoJSON LineString.

Installation

npm install @mapbox/polyline

Note that the old package polyline has been deprecated in favor of @mapbox/polyline (the old package remain but won't receive updates).

Example

var polyline = require('@mapbox/polyline');

// returns an array of lat, lon pairs
polyline.decode('_p~iF~ps|U_ulLnnqC_mqNvxq`@');

// returns an array of lat, lon pairs from polyline6 by passing a precision parameter
polyline.decode('cxl_cBqwvnS|Dy@ogFyxmAf`IsnA|CjFzCsHluD_k@hi@ljL', 6);

// returns a GeoJSON LineString feature
polyline.toGeoJSON('_p~iF~ps|U_ulLnnqC_mqNvxq`@');

// returns a string-encoded polyline
polyline.encode([[38.5, -120.2], [40.7, -120.95], [43.252, -126.453]]);

// returns a string-encoded polyline from a GeoJSON LineString
polyline.fromGeoJSON({ "type": "Feature",
  "geometry": {
    "type": "LineString",
    "coordinates": [[-120.2, 38.5], [-120.95, 40.7], [-126.453, 43.252]]
  },
  "properties": {}
});

API Documentation

Command line

Install globally or run ./node_modules/.bin/polyline.

Send input via stdin and use --decode, --encode, --toGeoJSON, or --fromGeoJSON flags. If omitted will default to --decode.

Example :

cat file.json | ./bin/polyline.bin.js --fromGeoJSON > result.txt