Module geohash 

Geohash encoding/decoding for spatial indexing.

Geohash is an interleaved Z-order curve over (longitude, latitude) that maps 2D coordinates to a 1D string using base-32 encoding. Nearby points share common prefixes, enabling fast proximity queries via string prefix matching on standard B-tree indexes.

Properties:

• Precision 1: ~5,000 km cells
• Precision 6: ~1.2 km × 0.6 km cells (default)
• Precision 8: ~19 m × 19 m cells
• Precision 12: ~3.7 cm × 1.9 cm cells (maximum practical)

References:

• Gustavo Niemeyer, geohash.org (2008)
• Wikipedia: Geohash

Enums

Direction

Direction for neighbor computation.

Functions

geohash_cover

Compute the set of geohash cells that cover a bounding box at the given precision. Useful for range queries: “find all geohash prefixes that overlap this region.”

geohash_decode

Decode a geohash string to its bounding box.

geohash_decode_center

Decode a geohash to its center point (longitude, latitude).

geohash_encode

Encode a (longitude, latitude) coordinate to a geohash string.

geohash_neighbor

Compute the geohash of a neighbor cell in the given direction.

geohash_neighbors

Compute all 8 neighbor geohashes.