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geo

3.4.3
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Encodes and decodes WKB, WKT, and GeoJSON formats.

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README.md 

# Geo



[![Build Status](https://travis-ci.org/bryanjos/geo.svg?branch=master)](https://travis-ci.org/bryanjos/geo)

[![Module Version](https://img.shields.io/hexpm/v/geo.svg)](https://hex.pm/packages/geo)

[![Hex Docs](https://img.shields.io/badge/hex-docs-lightgreen.svg)](https://hexdocs.pm/geo/)

[![Total Download](https://img.shields.io/hexpm/dt/geo.svg)](https://hex.pm/packages/geo)

[![License](https://img.shields.io/hexpm/l/geo.svg)](https://github.com/bryanjos/geo/blob/master/LICENSE)

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



A collection of GIS functions. Handles conversions to and from well-known test (WKT), well-known binary (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](https://github.com/bryanjos/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, "~> 3.4"}

  ]

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 Jason as the JSON parser



iex(1)> Geo.JSON.encode(point)

{:ok, %{ "type" => "Point", "coordinates" => [100.0, 0.0] }}



iex(2)> point = Jason.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) |> Jason.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/bryanjos/geo/blob/master/LICENSE.md).