libpysal.cg.alpha_shape¶
-
libpysal.cg.
alpha_shape
(xys, alpha)[source]¶ Alpha-shape delineation (Edelsbrunner, Kirkpatrick & Seidel, 1983) from a collection of points …
- Parameters
- xys
ndarray
(N, 2) array with one point per row and coordinates structured as X and Y
- alpha
python:float
Alpha value to delineate the alpha-shape
- xys
- Returns
- shapes
GeoSeries
Polygon(s) resulting from the alpha shape algorithm. The GeoSeries object remains so even if only a single polygon is returned. There is no CRS included in the object.
- shapes
References
- Edelsbrunner, H., Kirkpatrick, D., & Seidel, R. (1983). On the shape of
a set of points in the plane. IEEE Transactions on information theory, 29(4), 551-559.
Examples
>>> pts = np.array([[0, 1], [3, 5], [4, 1], [6, 7], [9, 3]]) >>> alpha = 0.1 >>> poly = alpha_shape(pts, alpha) >>> poly 0 POLYGON ((0.00000 1.00000, 3.00000 5.00000, 6.... dtype: geometry >>> poly.centroid 0 POINT (4.69048 3.45238) dtype: geometry