# Geo
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
Also includes an encoder, decoder, and formatter for using PostGIS data types with Postgrex
```
defp deps do
[{:geo, "~> 0.8.0"}]
end
```
## Examples
* Encode and decode WKT and EWKT
```
iex(1)> point = Geo.WKT.decode("POINT(30 -90)")
%Geo.Geometry{type: :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.Geometry{type: :point, coordinates: [30, -90], srid: 4326}
```
* Encode and decode WKB and EWKB
```
iex(1)> point = Geo.WKB.decode("0101000000000000000000F03F000000000000F03F")
%Geo.Geometry{ type: :point, coordinates: [1.0, 1.0], srid: nil }
iex(2)> Geo.WKB.encode(point)
"00000000013FF00000000000003FF0000000000000"
iex(3)> point = Geo.WKB.decode("0101000020E61000009EFB613A637B4240CF2C0950D3735EC0")
%Geo.Geometry{ type: :point, coordinates: [36.9639657, -121.8097725], srid: 4326 }
iex(4)> Geo.WKB.encode(point)
"0020000001000010E640427B633A61FB9EC05E73D350092CCF"
```
* Encode and decode GeoJSON
```
iex(1)> point = Geo.JSON.decode("{ \"type\": \"Point\", \"coordinates\": [100.0, 0.0] }")
%Geo.Geometry{ type: :point, coordinates: [100.0, 0.0], srid: nil }
iex(2)> Geo.JSON.encode(point)
"{\"type\":\"Point\",\"coordinates\":[100.0,0.0]}"
```
* Encoder, Decoder, and Formatter to be used with Postgrex for PostGIS data types
```
iex(1)> opts = [hostname: "localhost",
...(1)> username: "postgres", database: "geo_postgrex_test",
...(1)> encoder: &Geo.PostGIS.encoder/3, decoder: &Geo.PostGIS.decoder/4,
...(1)> formatter: &Geo.PostGIS.formatter/1 ]
[hostname: "localhost", username: "postgres", database: "geo_postgrex_test",
encoder: &Geo.PostGIS.encoder/3, decoder: &Geo.PostGIS.decoder/4,
formatter: &Geo.PostGIS.formatter/1]
iex(2)> {:ok, pid} = Postgrex.Connection.start_link(opts)
{:ok, #PID<0.115.0>}
iex(3)> geo = %Geo.Geometry{type: :point, coordinates: [30, -90], srid: 4326}
%Geo.Geometry{coordinates: [30, -90], srid: 4326, type: :point}
iex(4)> {:ok, _} = Postgrex.Connection.query(pid, "CREATE TABLE point_test (id int, geom geometry(Point, 4326))")
{:ok,
%Postgrex.Result{columns: nil, command: :create_table, num_rows: 0, rows: nil}}
iex(5)> {:ok, _} = Postgrex.Connection.query(pid, "INSERT INTO point_test VALUES ($1, $2)", [42, geo])
{:ok, %Postgrex.Result{columns: nil, command: :insert, num_rows: 1, rows: nil}}
iex(6)> Postgrex.Connection.query(pid, "SELECT * FROM point_test")
{:ok,
%Postgrex.Result{columns: ["id", "geom"], command: :select, num_rows: 1,
rows: [{42,
%Geo.Geometry{coordinates: [30.0, -90.0], srid: 4326, type: :point}}]}}
```