gaker / spatial_hash_ex

Elixir library for calculating spatial hashes for points and geometries

SpatialHash

A library for calculating spatial hashes for points and geometries. This is most useful for building spatial databases with very fast indexing.

Installation

defp deps do
  [{:spatial_hash, "~> 0.1.0"}]
end

Usage

Full Documentation

The SpatialHash module provides a hash function that takes a single point on any dimension as an array of coordinates and an array of gridding properties for each dimension. Grid properties are specified as a tuple of coordinate min and max as well as a step value for the grid spacing. Convenience function of SpatialHash.world_grid() is provided that returns a grid of the entire world in degress with step value roughly equivalent to 10 meters.

A hash_range function is also provided that takes an Envelope or Geometry and returns the range covered in each dimension.

SpatialHash.hash_range(
  %Envelope{
    min_x: -90.082756,
    min_y: 29.949766,
    max_x: -90.079484,
    max_y: 29.952280
  }, [{-180, 180, 0.01}, {-90, 90, 0.01}]) // -> [8991..8992, 11994..11995]

SpatialHash.hash_range(
  %{type: "LineString", coordinates: [
    { -90.082746, 29.950955},
    {-90.081453, 29.952280},
    {-90.079489, 29.949770}
  ]}, SpatialHash.world_grid) // -> [89917..89920, 119949..119952]