geopandas.GeoSeries.polygonize

GeoSeries.polygonize(node=True, full=False)

Creates polygons formed from the linework of a GeoSeries.

Polygonizes the GeoSeries that contain linework which represents the edges of a planar graph. Any geometry type may be provided as input; only the constituent lines and rings will be used to create the output polygons.

Lines or rings that when combined do not completely close a polygon will be ignored. Duplicate segments are ignored.

Unless you know that the input GeoSeries represents a planar graph with a clean topology (e.g. there is a node on both lines where they intersect), it is recommended to use node=True which performs noding prior to polygonization. Using node=False will provide performance benefits but may result in incorrect polygons if the input is not of the proper topology.

When full=True, the return value is a 4-tuple containing output polygons, along with lines which could not be converted to polygons. The return value consists of 4 elements or varying lenghts:

• GeoSeries of the valid polygons (same as with full=False)

• GeoSeries of cut edges: edges connected on both ends but not part of polygonal output

• GeoSeries of dangles: edges connected on one end but not part of polygonal output

• GeoSeries of invalid rings: polygons that are formed but are not valid (bowties, etc)

Parameters:

nodebool, default True

Perform noding prior to polygonization, by default True.

fullbool, default False

Return the full output composed of a tuple of GeoSeries, by default False.

Returns:

GeoSeries | tuple(GeoSeries, GeoSeries, GeoSeries, GeoSeries)

GeoSeries with the polygons or a tuple of four GeoSeries as (polygons, cuts, dangles, invalid)

Examples

>>> from shapely.geometry import LineString
>>> s = geopandas.GeoSeries([
...     LineString([(0, 0), (1, 1)]),
...     LineString([(0, 0), (0, 1), (1, 1), (1, 0), (0, 0)]),
...     LineString([(0.5, 0.2), (0.5, 0.8)]),
... ])
>>> s.polygonize()
0        POLYGON ((0 0, 0.5 0.5, 1 1, 1 0, 0 0))
1    POLYGON ((0.5 0.5, 0 0, 0 1, 1 1, 0.5 0.5))
Name: polygons, dtype: geometry

>>> polygons, cuts, dangles, invalid = s.polygonize(full=True)