node-geohash
Geohash library for nodejs.
Install
npm install ngeohash
Usage
var geohash = ;console;// prints ww8p1r4t8var latlon = geohash;console;console;
Basic Methods
geohash.encode (latitude, longitude, precision=9)
Encode a pair of latitude and longitude values into a geohash. The third argument is optional, you can specify a length of this hash string, which also affects the precision of the geohash.
geohash.decode (hashstring)
Decode a hash string into pair of latitude and longitude values. A javascript object is returned with latitude
and longitude
keys.
geohash.decode_bbox (hashstring)
Decode hashstring into a bounding box that matches it. Data is returned as a four-element array: [minlat, minlon, maxlat, maxlon]
.
geohash.bboxes (minlat, minlon, maxlat, maxlon, precision=9)
Get all hashstringes between [minlat, minlon]
and [maxlat, maxlon]
. These keys can be used to find a poi stored in the cache with hashstring keys. eg. show all points in the visible range of map
geohash.neighbor (hashstring, direction)
Find the neighbor of a geohash string in certain direction. Direction is a two-element array, i.e. [1,0]
means north, [-1,-1]
means southwest.
geohash.neighbors (hashstring)
Find all 8 geohash neighbors [n, ne, e, se, s, sw, w, nw]
of a geohash string. This method is more efficient than running the geohash.neighbor method multiple times for all directions. array: [hashstr1, hashstr2, ... ]
Integer Methods
Note that integer precision is capped at 52bits in Javscript. These are just regular javascript floating point numbers, but the functionality should mimic other uint64 geohash functions in geohash libraries for other languages and are compatible with the geohash integers produced by them, however any geohash integer encoded in anything more than 52bits will be resolved to 52bits resolution.
geohash.encode_int (latitude, longitude, bitDepth=52)
Encode a pair of latitude and longitude values into a geohash integer. The third argument is optional, you can specify the bitDepth
of this number, which affects the precision of the geohash but also must be used consistently when decoding. Bit depth must be even.
geohash.decode_int (hashinteger, bitDepth=52)
Decode a integer geohashed number into pair of latitude and longitude value approximations. A javascript object is returned with latitude
and longitude
keys. You should also provide the bitDepth
at which to decode the number (ie. what bitDepth the number was originally produced with), but will default to 52.
geohash.decode_bbox_int (hashinteger, bitDepth=52)
Decode an integer geohash into the bounding box that matches it. Data is returned as a four-element array: [minlat, minlon, maxlat, maxlon]
.
geohash.bboxes_int (minlat, minlon, maxlat, maxlon, bitDepth=52)
Get all geohash integers between [minlat, minlon]
and [maxlat, maxlon]
. These keys can be used to find a poi stored in the cache with geohash integer keys. eg. show all points in the visible range of map
geohash.neighbor_int (hashinteger, direction, bitDepth=52)
Find the neighbor of a geohash integer in certain direction. Direction is a two-element array, i.e. [1,0]
means north, [-1,-1]
means southwest. The bitDepth
should be specified, but defaults to 52 bits.
geohash.neighbors_int (hashinteger, bitDepth=52)
Find all 8 neighbors [n, ne, e, se, s, sw, w, nw]
of a geohash integer. This method is more efficient than running the geohash.neighbor method multiple times for all directions. The bitDepth
should be specified, but defaults to 52 bits.
Node-Geohash for browser
We recently added a browserify hook in npm install
. ngeohash.js
will be generated during npm install
, and
you can use this file in your javascript application for browser.
About Geohash
Check Wikipedia for more information.
See Also
Geohash.rs: node-geohash ported to Rust: A rust library for geohash.
License
node-geohash is open sourced under MIT License, of course.
Donation
I'm now accepting donation on liberapay, if you find my work helpful and want to keep it going.