Geohash grid

Base32-encoded rectangular grid. Each appended character refines the cell, so geohashes are hierarchical and string-prefix comparable.

The interactive explorer below is rendered with deck.gl and behaves like the h3geo.org map: the geohash precision follows the zoom level and cells are generated in the browser for whatever is in view — zoom in for finer cells, zoom out for coarser. Two neighbouring precisions are shown at once — the current level with a darker, heavier border and the next finer level with a lighter, thinner one — so the base-32 nesting stays visible. The lattice and base-32 encoder are the exact ones M3S uses (the shared m3s_core geohash encoder), reproduced in JavaScript so the cell ids and edges match M3S. GIS-native (lon, lat) order is used throughout.

Why Geohash?

The default for database indexing: each cell is one short base-32 string, and a shared prefix means “same area”, so range scans and prefix queries work in any plain string index — Redis, MongoDB, Elasticsearch and PostGIS all support it natively. Two caveats: cells are rectangles whose aspect ratio flips with each precision step, and prefix similarity breaks at cell boundaries (two points metres apart can share no prefix at all). For analysis with uniform neighbours use H3 grid; for codes meant to be read aloud or printed, Plus Codes grid was designed for exactly that.

Usage

Encode a point and tile a small bounding box around Paris — same result in Python and JavaScript (both call the shared core):

Python

import m3s

cell = m3s.Geohash.from_geometry((2.35, 48.86))            # (lon, lat)
cells = m3s.Geohash.from_geometry((2.2, 48.8, 2.4, 48.9))  # bbox
print(cell.id, len(cells))

JavaScript

import * as m3s from "m3s";
await m3s.ready();

const cell = m3s.Geohash.fromPoint(2.35, 48.86);            // (lon, lat)
const cells = m3s.Geohash.fromBbox([2.2, 48.8, 2.4, 48.9]); // bbox
console.log(cell.id, cells.length);

from _deckmap import DeckExplorer, read_grid_js


DeckExplorer(
    center=(9.5, 48.5),
    zoom=5,
    grid_js=read_grid_js("geohash"),
    hover="#E69F00",
    wasm=True,
)