# Geo

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[![Last Updated](https://img.shields.io/github/last-commit/felt/geo.svg)](https://github.com/felt/geo/commits/master)

A collection of GIS functions. Handles conversions to and from well-known text (WKT), well-known binary (WKB), and GeoJSON for the following geometries:

* Point
* PointZ
* PointM
* PointZM
* LineString
* LineStringZ
* LineStringZM
* Polygon
* PolygonZ
* MultiPoint
* MultiPointZ
* MultiLineString
* MultiLineStringZ
* MultiLineStringZM
* MultiPolygon
* MultiPolygonZ
* GeometryCollection

_Note_: If you are looking for the Postgrex PostGIS extension, check out [geo_postgis](https://github.com/felt/geo_postgis).

_Note_: If you are looking to do geospatial calculations in memory with Geo's structs, check out [topo](https://github.com/pkinney/topo).

```elixir
defp deps do
  [
    {:geo, "~> 4.0"}
  ]
end
```

## Examples

Encode and decode WKT and EWKT:

```elixir
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:

```elixir
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.

```elixir
# Examples using JSON as the JSON parser

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

iex(2)> point = JSON.decode!("{\"type\": \"Point\", \"coordinates\": [100.0, 0.0] }") |> Geo.JSON.decode
{:ok, %Geo.Point{coordinates: {100.0, 0.0}, srid: 4326, properties: %{}}

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

## Copyright and License

Copyright (c) 2014 Bryan Joseph

Released under the MIT License, which can be found in the repository in [`LICENSE`](https://github.com/felt/geo/blob/master/LICENSE.md).