How to turn an array of indices into a binary 3D numpy array?

user_14046024 0
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I have array of vertices from an stl file which i converted to a 2D numpy array. Here's some of it as an example:

print(vertices.shape)

(67748, 3)

I need to turn these into a 3D binary array where each element = 1 where the index is given by the vertices array.

Minimal reproducible example (expected output) using a 5 x 3 vertices array instead of 67748 x 3:

verts = np.array([[ 77, 239,  83],
 [100, 237,  88],
 [100, 149,  94],
 [100, 220, 128],
 [100, 145,  86]])

voxels = np.zeros((256,256,256)).astype(int)

voxels[77,239,83] = 1
voxels[100,149,94] = 1
voxels[100,237,88] = 1
voxels[100,220,128] = 1
voxels[100,145, 86] = 1
numpy arrays python
2 Answers

You can use np.put and np.ravel_multi_index

np.put(voxel_array, 
       np.ravel_multi_index(vertices.T, 
                            voxel_array.shape), 
       1)

And then:

np.where(voxel_array)
Out[]: 
(array([ 77, 100, 100, 100, 100], dtype=int64),
 array([239, 145, 149, 220, 237], dtype=int64),
 array([ 83,  86,  94, 128,  88], dtype=int64))
user_44277770

Answer from Michael Szczesny in the comments:

for x, y, z in vertices: voxel_array[x, y, z] = 1

This works just as well as Daniel F's but is easier to understand. Both take 0.0 seconds to run on 256 x 265 x 265 array

user_140460240
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