Geohash-poly
npm install geohash-poly
Transform a GeoJSON (Multi)Polygon to a list of geohashes that cover it.
Method used is pretty brute-force, but still relatively quick compared to alternative implementations if hash precision is not too granular. Creates an envelope around poly, and iterates over rows and columns, including relevant hashes with respect to hashMode
.
Streaming
Hashes can be streamed. Each _read will generate a row of hashes into buffer, as some form of throttling. This allows massive polygons with high precision hashes to avoid memory constraint issues. If your polys have the potential to hit memory issues, use this method.
If you specify rowMode as true, such as .stream({..., rowMode: true, ...})
, each chunk in the stream will be an array using streams2 objectMode.
var through2 = ; var polygon = -122350051 47702893 -122344774 47702877 -122344777 4770324 -122341982 47703234 -122341959 47701421 -122339749 47701416 -122339704 4769776 -122341913 47697797 -122341905 47697071 -122344576 47697084 -122344609 47697807 -122349999 47697822 -122350051 47702893 ; var stream = geohashpoly; stream ;
Results in the hashes spit out line by line to the console.
Standard
If you just want your hashes out in an array, use this.
var polygon = -122350051 47702893 -122344774 47702877 -122344777 4770324 -122341982 47703234 -122341959 47701421 -122339749 47701416 -122339704 4769776 -122341913 47697797 -122341905 47697071 -122344576 47697084 -122344609 47697807 -122349999 47697822 -122350051 47702893 ; ;
Results in:
[ 'c22zrgg', 'c22zrgu', 'c22zrgv', 'c22zrgy', 'c22zrgz', 'c23p25b', 'c22zrge', 'c22zrgs', 'c22zrgt', 'c22zrgw', 'c22zrgx', 'c23p258', 'c23p259', 'c23p25d', 'c22zrg7', 'c22zrgk', 'c22zrgm', 'c22zrgq', 'c22zrgr', 'c23p252', 'c23p253', 'c23p256', 'c22zrg5', 'c22zrgh', 'c22zrgj', 'c22zrgn', 'c22zrgp', 'c23p250', 'c23p251', 'c23p254' ]
Also, integer geohashes are available.
;
Results in:
[ 5940702973,
5940702975,
5941052501,
5940702972,
5940702974,
5941052500,
5940702969,
5940702971,
5941052497,
5940702968,
5940702970,
5941052496 ]
Options
coords
: coordinate array for the geojson shape. requiredprecision
: geohash precision (eg. "gfjf1" is a precision 5 geohash).rowMode
: allows for processing of geohashes by row.hashMode
: defines filtering of returned geohashes. See below.integerMode
: (true/false) Outputs integer versions of geohashes. Default precision for integer mode is 32 bits.
hashMode
The hashMode
option can be used to specify which hashes to return. Defaults to 'inside'
.
'inside'
: return hashes whose center points fall inside the shape.'extent'
: return all hashes which make up the bounding box of the shape.'intersect'
: return all hashes that intersect with the shape. Use the'threshold'
option to specify a percentage of least coverage. Seeexamples/streaming.js
.
Command Line
You can also install as a command line util via
npm install geohash-poly -g
command line usage
Here are some examples of running it:
geohash-poly --csv=true --precision=9 --geocode=true "[[[-122.350051, 47.702893 ], [-122.344774, 47.702877 ], [-122.344777, 47.70324 ], [-122.341982, 47.703234 ], [-122.341959, 47.701421 ], [-122.339749, 47.701416 ], [-122.339704, 47.69776 ], [-122.341913, 47.697797 ], [-122.341905, 47.697071 ], [-122.344576, 47.697084 ], [-122.344609, 47.697807 ], [-122.349999, 47.697822 ], [-122.350051, 47.702893 ]]]"
Where additional command line switches are
- --csv=true output csv. default output is ndjson
- --geocode=true to add the lat and lon to the output
All of the standard options are supported as well.