Remove simplex from scipy Delaunay triangulation

Question

I have a set of points, from which I calculate a Delaunay triangulation using the scipy.spatial.Delaunay function. Something along the following for example:

import numpy as np
from scipy.spatial import Delaunay

tri = Delaunay(np.random.rand(10,2))

What I want to do after this is calculated is remove a simplex. Is there an easy way to do this? I notice the Delaunay object has a method for add_point but nothing for remove_point or remove_simplex.

The way I see it, I have two options. I know the list of points myself so I simply remove the necessary points and re-calculate the Delaunay triangulation. I hope to avoid this as it can become inefficient if I have to re-calculate a lot for a lot of points. The other option I can see is to directly edit the object parameters myself, but this seems like a potentially dangerous method. Does anyone have any suggestions of a better method?

@ali_m For generating polygonal meshes (potentially in high dimensions). I create a baseline mesh using Delaunay triangulation, but I then need to adjust the mesh by doing things like moving vertices around or removing simplexes. — zephyr, Feb 09 '16 at 20:59
I guess my question is which methods of the `Delaunay` instance still need to work correctly after you've removed simplices? — ali_m, Feb 09 '16 at 21:02
Not 100% sure yet, but at the very least, I need the information stored in it. However I expect I'll eventually need information like the paraboloid scale and shift or the convex hull. — zephyr, Feb 10 '16 at 15:56

score 3 · Answer 1 · answered May 03 '17 at 09:08

The Delaunay result is a numpy object.You can choose the simplex you need.

import numpy as np
from scipy.spatial import Delaunay
import matplotlib.pyplot as plt

points = np.random.rand(30,2)
tri = Delaunay(points).simplices.copy()

plt.triplot(points[:,0], points[:,1], tri, linewidth=0.5)
plt.show()

tri_another = tri[0:10,:]
print(len(tri))
print(len(tri_another))
plt.triplot(points[:,0], points[:,1], tri_another, linewidth=0.5)
plt.show()

Remove simplex from scipy Delaunay triangulation

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