GeoDataFrame.concave_hull

Return a GeoSeries of geometries representing the concave hull of vertices of each geometry. A concave hull is a concave or convex Polygon containing all the vertices in each geometry. For two vertices, the hull collapses to a LineString; for one vertex, it collapses to a Point. The hull is constructed by removing border triangles of the Delaunay triangulation. The ratio determines the maximum edge-length threshold by interpolating between the shortest and longest edges in the triangulation.

Signature

concave_hull(ratio=0.0, allow_holes=False)

Parameters

float

default:"0.0"

Number in the range [0, 1]. Higher numbers will include fewer vertices in the hull.

bool

default:"False"

If set to True, the concave hull may have holes.

Returns

GeoSeries

See also

GeoSeries.convex_hull: convex hull geometry

The algorithm considers only the vertices of each geometry. As a result, the hull may not fully enclose the edges of the input geometry. Increasing ratio should resolve that case.Sedona and GeoPandas use the JTS and GEOS implementations, respectively. When candidate border triangles have the same edge length and area, the implementations may choose different, equally valid concave hulls.

Examples

>>> from sedona.spark.geopandas import GeoSeries
>>> from shapely.geometry import MultiPoint
>>> s = GeoSeries(
...     [MultiPoint([(0, 0), (1, 0), (0.5, 0.5), (1, 1), (0, 1)])]
... )
>>> s.concave_hull(ratio=0.3)
0    POLYGON ((0 0, 0 1, 0.5 0.5, 1 1, 1 0, 0 0))
dtype: geometry

​Signature

​Parameters

​Returns

​Examples

Signature

Parameters

Returns

Examples