henrylearn2rock / latlon-geohash

Gustavo Niemeyer’s geocoding system

geohash

Functions to convert a geohash to/from a latitude/longitude point, and to determine bounds of a geohash cell and find neighbours of a geohash.

Methods summary:

• encode: latitude/longitude point to geohash
• decode: geohash to latitude/longitude
• bounds of a geohash cell
• adjacent neighbours of a geohash

Install

in browser

Download the JavaScript source and reference in HTML page using:

<script src="js/latlon-geohash.js"></script>

from npm

npm install --save latlon-geohash

Usage

• Geohash.encode(lat, lon, [precision]): encode latitude/longitude point to geohash of given precision (number of characters in resulting geohash); if precision is not specified, it is inferred from precision of latitude/longitude values.
• Geohash.decode(geohash): return { lat, lon } of centre of given geohash, to appropriate precision.
• Geohash.bounds(geohash): return { sw, ne } bounds of given geohash.
• Geohash.adjacent(geohash, direction): return adjacent cell to given geohash in specified direction (N/S/E/W).
• Geohash.neighbours(geohash): return all 8 adjacent cells (n/ne/e/se/s/sw/w/nw) to given geohash.

Note to obtain neighbours as an array, you can use

var neighboursObj = Geohash.neighbours(geohash);
var neighboursArr = Object.keys(neighboursObj).map(function(n) { return neighboursObj[n]; });

Note that the parent of a geocode is simply geocode.slice(0, -1).

Import within node.js

var Geohash = require('latlon-geohash');

Further details

More information (with interactive conversion) at www.movable-type.co.uk/scripts/geohash.html.

Full JsDoc at www.movable-type.co.uk/scripts/js/latlon-geohash/docs/Geohash.html.