geopandas.GeoSeries.simplify_coverage#

GeoSeries.simplify_coverage(tolerance, *, simplify_boundary=True)[source]#

Return a GeoSeries containing a simplified representation of polygonal coverage.

Assumes that the GeoSeries forms a polygonal coverage. Under this assumption, the method simplifies the edges using the Visvalingam-Whyatt algorithm, while preserving a valid coverage. In the most simplified case, polygons are reduced to triangles.

A GeoSeries of valid polygons is considered a coverage if the polygons are:

  • Non-overlapping - polygons do not overlap (their interiors do not intersect)

  • Edge-Matched - vertices along shared edges are identical

The method allows simplification of all edges including the outer boundaries of the coverage or simplification of only the inner (shared) edges.

If there are other geometry types than Polygons or MultiPolygons present, the method will raise an error.

If the geometry is polygonal but does not form a valid coverage due to overlaps, it will be simplified but it may result in invalid coverage topology.

Requires Shapely >= 2.1.

Added in version 1.1.0.

Parameters:
tolerancefloat

The degree of simplification roughly equal to the square root of the area of triangles that will be removed. It has the same units as the coordinate reference system of the GeoSeries. For example, using tolerance=100 in a projected CRS with meters as units means a distance of 100 meters in reality.

simplify_boundary: bool (default True)

By default (True), simplifies both internal edges of the coverage as well as its boundary. If set to False, only simplifies internal edges.

See also

simplify

simplification of individual geometries

Examples

>>> from shapely.geometry import Polygon
>>> s = geopandas.GeoSeries(
...     [
...         Polygon([(0, 0), (1, 1.1), (2, 0), (1.5, 1), (2, 2), (0, 2)]),
...         Polygon([(2, 0), (4, 0), (4, 2), (2, 2), (1.5, 1)]),
...     ]
... )
>>> s
0    POLYGON ((0 0, 1 1.1, 2 0, 1.5 1, 2 2, 0 2, 0 0))
1           POLYGON ((2 0, 4 0, 4 2, 2 2, 1.5 1, 2 0))
dtype: geometry

>>> s.simplify_coverage(1)
0         POLYGON ((2 0, 2 2, 0 2, 2 0))
1    POLYGON ((2 0, 4 0, 4 2, 2 2, 2 0))
dtype: geometry

>>> s.simplify_coverage(1, simplify_boundary=False)
0    POLYGON ((2 0, 2 2, 0 2, 0 0, 1 1.1, 2 0))
1           POLYGON ((2 0, 4 0, 4 2, 2 2, 2 0))
dtype: geometry