# `Meridian.Builder.Geohash`
[🔗](https://github.com/code-shoily/meridian/blob/v0.1.0/lib/meridian/builder/geohash.ex#L1)

Builds graphs from geohash rectangular grids.

Requires the optional `:geohash` dependency.

Uses a flood-fill approach starting from the center of the bounding box
to discover all geohash cells that intersect the area.

## Topologies

  * `:rook` — 4 cardinal neighbors (default)
  * `:queen` — 8 neighbors including diagonals

## Examples

    iex> graph =
    ...>   Meridian.Graph.new(kind: :undirected)
    ...>   |> Meridian.Builder.Geohash.grid(
    ...>        sw: {40.6, -74.1},
    ...>        ne: {40.8, -73.9},
    ...>        precision: 5,
    ...>        topology: :rook
    ...>      )
    iex> Meridian.Graph.node_count(graph) >= 1
    true

# `grid`

```elixir
@spec grid(
  Meridian.Graph.t(),
  keyword()
) :: Meridian.Graph.t()
```

Creates a graph covering a bounding box with geohash cells.

## Options

  * `:sw` — southwest corner `{lat, lon}` (required)
  * `:ne` — northeast corner `{lat, lon}` (required)
  * `:precision` — geohash character length, 1–12 (required)
  * `:topology` — `:rook` (default) or `:queen`
  * `:node_data_fn` — function `(geohash :: String.t()) -> map`

## Examples

    iex> graph =
    ...>   Meridian.Graph.new(kind: :undirected)
    ...>   |> Meridian.Builder.Geohash.grid(sw: {0.0, 0.0}, ne: {0.1, 0.1}, precision: 5)
    iex> Meridian.Graph.node_count(graph) >= 1
    true

---

*Consult [api-reference.md](api-reference.md) for complete listing*