/geo

A collection of GIS functions for Elixir

Primary LanguageElixirMIT LicenseMIT

Geo

Build Status

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

  • Point
  • LineString
  • Polygon
  • MultiPoint
  • MulitLineString
  • MultiPolygon
  • 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, "~> 2.0"}]
end

Documentation

Examples

  • Encode and decode WKT and EWKT

    iex(1)> 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)> 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)
%{ "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]}"

Development

After you got the dependencies via mix deps.get make sure that:

  • postgis is installed
  • your postgres user has the database "geo_postgrex_test"
  • your postgres db user can login without a password or you set the PGPASSWORD environment variable appropriately

Then you can run the tests as you are used to with mix test.