Geometry

Utility geometry operations functions.

Functions

srai.geometry.merge_disjointed_gdf_geometries(gdf)

Merges geometries from a GeoDataFrame into a single MultiPolygon.

Input geometries are expected to be disjointed.

PARAMETER	DESCRIPTION
gdf	GeoDataFrame with geometries to merge. TYPE: gpd.GeoDataFrame

RETURNS	DESCRIPTION
MultiPolygon	Merged polygon TYPE: MultiPolygon

Source code in srai/geometry.py

def merge_disjointed_gdf_geometries(gdf: gpd.GeoDataFrame) -> MultiPolygon:
    """
    Merges geometries from a GeoDataFrame into a single MultiPolygon.

    Input geometries are expected to be disjointed.

    Args:
        gdf (gpd.GeoDataFrame): GeoDataFrame with geometries to merge.

    Returns:
        MultiPolygon: Merged polygon
    """
    return merge_disjointed_polygons(list(gdf.geometry))

srai.geometry.flatten_geometry_series(geometry_series)

Flatten all geometries from a series into a list of BaseGeometries.

Source code in srai/geometry.py

def flatten_geometry_series(geometry_series: gpd.GeoSeries) -> list[BaseGeometry]:
    """Flatten all geometries from a series into a list of BaseGeometries."""
    geometries: list[BaseGeometry] = (
        seq([flatten_geometry(geometry) for geometry in geometry_series]).flatten().to_list()
    )
    return geometries

srai.geometry.merge_disjointed_polygons(polygons)

Merges all polygons into a single MultiPolygon.

Input polygons are expected to be disjointed.

PARAMETER	DESCRIPTION
polygons	List of polygons to merge TYPE: List[Union[Polygon, MultiPolygon]]

RETURNS	DESCRIPTION
MultiPolygon	Merged polygon TYPE: MultiPolygon

Source code in srai/geometry.py

def merge_disjointed_polygons(polygons: list[Union[Polygon, MultiPolygon]]) -> MultiPolygon:
    """
    Merges all polygons into a single MultiPolygon.

    Input polygons are expected to be disjointed.

    Args:
        polygons (List[Union[Polygon, MultiPolygon]]): List of polygons to merge

    Returns:
        MultiPolygon: Merged polygon
    """
    single_polygons = []
    for geom in polygons:
        if isinstance(geom, Polygon):
            single_polygons.append(geom)
        else:
            single_polygons.extend(geom.geoms)
    return MultiPolygon(single_polygons)

srai.geometry.remove_interiors(geometry)

Close polygon holes by limitation to the exterior ring.

PARAMETER	DESCRIPTION
geometry	Polygon to close. TYPE: Union[Polygon, MultiPolygon]

RETURNS	DESCRIPTION
Polygon	Closed polygon. TYPE: Polygon

Source code in srai/geometry.py

def remove_interiors(geometry: Union[Polygon, MultiPolygon]) -> Polygon:
    """
    Close polygon holes by limitation to the exterior ring.

    Args:
        geometry (Union[Polygon, MultiPolygon])): Polygon to close.

    Returns:
        Polygon: Closed polygon.
    """
    if isinstance(geometry, MultiPolygon):
        return unary_union([remove_interiors(sub_polygon) for sub_polygon in geometry.geoms])
    if geometry.interiors:
        return Polygon(list(geometry.exterior.coords))
    return geometry

srai.geometry.flatten_geometry(geometry)

Flatten all geometries into a list of BaseGeometries.

Source code in srai/geometry.py

def flatten_geometry(geometry: BaseGeometry) -> list[BaseGeometry]:
    """Flatten all geometries into a list of BaseGeometries."""
    if isinstance(geometry, BaseMultipartGeometry):
        geometries: list[BaseGeometry] = (
            seq([flatten_geometry(sub_geom) for sub_geom in geometry.geoms]).flatten().to_list()
        )
        return geometries
    return [geometry]

srai.geometry.buffer_geometry(geometry, meters)

Buffer geometry by a given radius in meters.

Projects geometry into azimuthal projection before applying buffer and then changes values back to WGS84 coordinates.

Doesn't work with polygons covering the whole earth (from -180 to 180 longitude).

PARAMETER	DESCRIPTION
geometry	Geometry to buffer. TYPE: BaseGeometry
meters	Radius distance in meters. TYPE: float

RETURNS	DESCRIPTION
BaseGeometry	Buffered geometry. TYPE: BaseGeometry

Source code in srai/geometry.py

def buffer_geometry(geometry: BaseGeometry, meters: float) -> BaseGeometry:
    """
    Buffer geometry by a given radius in meters.

    Projects geometry into azimuthal projection before applying buffer and then changes values
    back to WGS84 coordinates.

    Doesn't work with polygons covering the whole earth (from -180 to 180 longitude).

    Args:
        geometry (BaseGeometry): Geometry to buffer.
        meters (float): Radius distance in meters.

    Returns:
        BaseGeometry: Buffered geometry.
    """
    _lon, _lat = geometry.centroid.coords[0]

    aeqd_proj = pyproj.Proj(proj="aeqd", ellps="WGS84", datum="WGS84", lat_0=_lat, lon_0=_lon)
    wgs84_proj = pyproj.Proj(proj="latlong", ellps="WGS84")

    wgs84_to_aeqd = pyproj.Transformer.from_proj(wgs84_proj, aeqd_proj, always_xy=True).transform
    aeqd_to_wgs84 = pyproj.Transformer.from_proj(aeqd_proj, wgs84_proj, always_xy=True).transform

    projected_geometry = shapely_transform(wgs84_to_aeqd, geometry)
    bufferred_projected_geometry = projected_geometry.buffer(meters)

    return shapely_transform(aeqd_to_wgs84, bufferred_projected_geometry)