@spec assert_wgs84!(term()) :: :ok

Verifies the declared SRID for GeoTurf's WGS84 calculations.

An SRID of 4326 is accepted. nil is also accepted for compatibility with Geo's default structs, but means that the caller is asserting that the coordinates are WGS84; GeoTurf cannot infer a coordinate reference system from coordinate values alone.

Any other declared SRID raises ArgumentError. Reproject those coordinates before passing them to GeoTurf. If the coordinates are already WGS84 and only the metadata is stale, correct it explicitly with %{geometry | srid: 4326}. GeometryCollection children and list members are validated recursively.

@spec bbox([{number(), number()}] | Geo.geometry()) ::
  {number(), number(), number(), number()} | :error

Create a bounding box for a given Geo.geometry/0. Returns :error when the geometry or coordinate list is empty.

Examples

iex> Geo.Turf.Helpers.bbox(%Geo.Polygon{coordinates: [{1,1}, {1,3}, {3,3}, {3,1}]})
{1,1,3,3}

iex> Geo.Turf.Helpers.bbox([{1,1},{2,2},{3,3}])
{1,1,3,3}

@spec bbox_polygon({number(), number(), number(), number()}) :: Geo.Polygon.t()

Takes a bounding box tuple and returns it as a %Geo.Polygon{}.

The ring winds: SW → SE → NE → NW → SW. The returned polygon has the WGS84 SRID 4326.

Examples

iex> Geo.Turf.Helpers.bbox_polygon({0, 0, 10, 10})
%Geo.Polygon{coordinates: [[{0, 0}, {10, 0}, {10, 10}, {0, 10}, {0, 0}]], srid: 4326}

iex> Geo.Turf.Helpers.bbox_polygon({-180, -90, 180, 90})
%Geo.Polygon{coordinates: [[{-180, -90}, {180, -90}, {180, 90}, {-180, 90}, {-180, -90}]], srid: 4326}

@spec flatten_coords(Geo.geometry()) :: [{number(), number()}]

Flatten a t:Geo.geometry() to a simple list of coordinates

Examples

iex> Geo.Turf.Helpers.flatten_coords(%Geo.GeometryCollection{geometries: [
...>  %Geo.Point{coordinates: {1,1}},
...>  %Geo.Point{coordinates: {2,2}}
...> ]})
[{1,1}, {2,2}]