wojtekmach / geo

A collection of GIS functions for Elixir

Geo

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]}"