Crate geo_hash 

Geohash library

In simple terms geohash converts point into hash that can uniquely identify cell on the map of the world Hash length will determines size of the cell with following table illustrating approximate sizes

Hash Len	Width	Height
1	<=5km	5km
2	<=1.250km	625km
3	<=156km	156km
4	<=39.1km	19.5km
5	<=4.89km	4.89km
6	<=1.22km	0.61km
7	<=153m	153m
8	<=38.2m	19.1m
9	<=4.77m	4.77m
10	<=1.19m	0.596m
11	<=149mm	149mm
12	<=37.2mm	18.6mm

Note, width becomes smaller depending on how far coordinate is from equator

The important property of the resulting hash is that the closer coordinates are, the bigger common prefix is between two hashes.

Features

serde - Implements serde interface on GeoHash

Usage

Encode with static hash size

You can use Codec to ensure encoding will never fail at compile time by supplying it with length of the hash you desire

use geo_hash::Coordinate;
type CODEC = geo_hash::Codec::<9>;

let position = Coordinate::try_new(43.2203, 142.8635).expect("valid GPS coordinates");
let hash = CODEC::encode(position);
assert_eq!(hash, "xpttfun02");

Encode with dynamic hash size

You can use GeoHash::encode when you cannot know size of the hash at compile time, which will fail if hash length is not within range of 1..=12

use geo_hash::{GeoHash, Coordinate};

let position = Coordinate::try_new(43.2203, 142.8635).expect("valid GPS coordinates");
let hash = GeoHash::encode(position, 9).expect("to encode");
assert_eq!(hash, "xpttfun02");

Decode hash to determine approximate position

When you only have textual hash, you can determine its bounding box or as approximation position within this bounding box

use geo_hash::{GeoHash, Coordinate};

const COORD: Coordinate =  Coordinate::new(43.22027921676636, 142.86348581314087);

//This function only checks length
let hash = GeoHash::try_from_str("xpttfun02").expect("valid geohash");
assert_eq!(hash, "xpttfun02");
//This function will check validity of hash itself
let bbox = hash.decode_bbox().expect("we should have valid hash here");
assert_eq!(bbox.min(), Coordinate::new(43.22025775909424, 142.86346435546875));
assert_eq!(bbox.max(), Coordinate::new(43.22030067443848, 142.863507270813));
let position = bbox.position();
assert_eq!(position.coordinates(), COORD);

Structs

Bbox

Geo Bounded box describing geohash cell

Codec

Geohash codec

Coordinate

Coordinate

DecodeError

Geohash decoding error

GeoHash

GeoHash value encoded as base32 string

GeoHashPosition

Geohash position with margins of error

Enums

CoordinateError

Possible errors when creating Coordinate

Direction

Direction to select neighbor