Python中2D凸包的周长

Question

How can I calculate the perimeter of a convex hull in Python? I know SciPy has the area parameter for convex hulls; however, I need the perimeter .

Answer 1

You can iterate over the points of the convex hull and compute the distance between consecutive points:

import numpy as np
from scipy.spatial.qhull import ConvexHull
from scipy.spatial.distance import euclidean

points = np.random.rand(30, 2)
hull = ConvexHull(points)

vertices = hull.vertices.tolist() + [hull.vertices[0]]
perimeter = np.sum([euclidean(x, y) for x, y in zip(points[vertices], points[vertices][1:])])
print(perimeter)

Output

3.11

Note: You also need to add the pair (last, first)

UPDATE

As an alternative, given that the data is 2D, you can use hull.area . That is the value returned in the above method is equal to the value of the area property. If you want the real area , you need to query hull.volume .

Further

1. What is area in scipy convex hull