geo

by bryanjos

bryanjos /geo

A collection of GIS functions for Elixir

431 Stars 61 Forks Last release: about 1 month ago (v3.3.5) MIT License 326 Commits 47 Releases

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Geo

Build Status Hex.pm

A collection of GIS functions. Handles conversions to and from WKT, WKB, and GeoJSON for the following geometries:

  • Point
  • PointZ
  • PointM
  • PointZM
  • LineString
  • LineStringZ
  • Polygon
  • PolygonZ
  • MultiPoint
  • MultiPointZ
  • MuliLineString
  • MuliLineStringZ
  • MultiPolygon
  • MultiPolygonZ
  • GeometryCollection

Note: If you are looking for the Postgrex PostGIS extension, check out geo_postgis

Note: If you are looking to do geospatial calculations in memory with Geo's structs, check out topo

defp deps do
  [{:geo, "~> 3.0"}]
end

Documentation

Examples

  • Encode and decode WKT and EWKT
  iex(1)> {:ok, point} = Geo.WKT.decode("POINT(30 -90)")
  %Geo.Point{ coordinates: {30, -90}, srid: nil}

iex(2)> Geo.WKT.encode!(point) "POINT(30 -90)"

iex(3)> point = Geo.WKT.decode!("SRID=4326;POINT(30 -90)") %Geo.Point{coordinates: {30, -90}, srid: 4326}

  • Encode and decode WKB and EWKB
  iex(1)> {:ok, point} = Geo.WKB.decode("0101000000000000000000F03F000000000000F03F")
  %Geo.Point{ coordinates: {1.0, 1.0}, srid: nil }

iex(2)> Geo.WKB.encode!(point) "00000000013FF00000000000003FF0000000000000"

iex(3)> point = Geo.WKB.decode!("0101000020E61000009EFB613A637B4240CF2C0950D3735EC0") %Geo.Point{ coordinates: {36.9639657, -121.8097725}, srid: 4326 }

iex(4)> Geo.WKB.encode!(point) "0020000001000010E640427B633A61FB9EC05E73D350092CCF"

  • Encode and decode GeoJSON

Geo only encodes and decodes maps shaped as GeoJSON. JSON encoding and decoding must be done before and after.

#Examples using Poison as the JSON parser

iex(1)> Geo.JSON.encode(point) {:ok, %{ "type" => "Point", "coordinates" => [100.0, 0.0] }}

iex(2)> point = Poison.decode!("{ "type": "Point", "coordinates": [100.0, 0.0] }") |> Geo.JSON.decode %Geo.Point{ coordinates: {100.0, 0.0}, srid: nil }

iex(3)> Geo.JSON.encode!(point) |> Poison.encode! "{"type":"Point","coordinates":[100.0,0.0]}"

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