Assertion check error in core.pyx

[rougier]

I'm using triangle for the glumpy library (glumpy.github.io) and since last update (triangle), I get some consistent errors:

Traceback (most recent call last):
  File "collection-triangles.py", line 51, in <module>
    I = triangulate(P)
  File "collection-triangles.py", line 26, in triangulate
    T = triangle.triangulate({'vertices': P[:,:2], 'segments': S}, "p")
  File "/usr/local/lib/python3.7/site-packages/triangle/tri.py", line 66, in triangulate
    tri, _ = triang(tri, opts)
  File "triangle/core.pyx", line 247, in triangle.core.triang
  File "triangle/core.pyx", line 219, in triangle.core.fin
  File "triangle/core.pyx", line 74, in triangle.core.ii._set
  File "triangle/core.pyx", line 115, in triangle.core._wrap.check
AssertionError

When I looked at your code, I've to admit I'm a bit puzzled by these lines:

cdef _wrap(triangulateio* c):

    cdef int _1 = 1
    cdef int _2 = 2
    cdef int _3 = 3
    cdef int _4 = 4

    def check():
        assert _1 == 1
        assert _2 == 2
        assert _3 == 3
        assert _4 == 4

Obviously in my case these assertions are False but I'm not sure to understand how this can be. Any advices on how to debug ?

In glumpy, I'm using the tiger.py to test.

[yuqli]

I have the exact same problem since last night! Have to learn some Cython but still, this error seems to be in the assert lines you quoted.

Since this library is updated three months ago and we both seem to be running into trouble since last night, maybe it's some changes in the Cython library. It could be a cdef int is no longer a Python int. I'm not sure why we need these lines either, though.

[drufat]

These assertions just make sure that assumptions about the number of dimensions of arrays in the C library and the python wrapper are actually correct. Do you think you can provide the contents of the P and S variables in the call

triangle.triangulate({'vertices': P[:,:2], 'segments': S}, "p")

which results in the assertion failure? Or I can extract them from the example you have given once I get back to my desk a little later.

[yuqli]

These assertions just make sure that assumptions about the number of dimensions of arrays in the C library and the python wrapper are actually correct. Do you think you can provide the contents of the P and S variables in the call

triangle.triangulate({'vertices': P[:,:2], 'segments': S}, "p")

which results in the assertion failure? Or I can extract them from the example you have given once I get back to my desk a little later.

Thanks for the prompted reply. If it helps, this is the data I used as inputs to the triangulate function which lead to the exact same error. Is it because my data points are 3D instead of 2D?

Code:

   poly = {'vertices': np.array(newpolypoints), 'segments': np.array(segments)}
    print(poly)
    # print poly
    # -- Triangulate
    t = triangle.triangulate(poly, "p")

Output:

{'vertices': array([[  9.24246154,  -2.02496154,  -8.79692308],
       [  6.71146154,  -4.45896154,  -8.79692308],
       [  2.78446154,  -8.23696154,  -8.79692308],
       [  1.91946154,  -9.06896154,  -8.79692308],
       [-11.00953846,   4.26003846,  -8.79692308],
       [ -3.68553846,  11.30403846,  -8.79692308]]), 'segments': array([[0, 1],
       [1, 2],
       [2, 3],
       [3, 4],
       [4, 5],
       [5, 0]])}
Traceback (most recent call last):
  File "triangulation.py", line 201, in <module>
    main()
  File "triangulation.py", line 195, in main
    res = my_triangulation(face_with_points[0])
  File "triangulation.py", line 146, in my_triangulation
    t = triangle.triangulate(poly, "p")
AttributeError: module 'triangle' has no attribute 'triangulate'

[yuqli]

I revised my code and when inputs are 2D arrays the assertionError no longer occurred. Thanks for the help! It could be a coincidence that @rougier and I have the exact same error at roughly the same time... I'm not sure about her/his exact issue though.

[drufat]

@yuqli
Yes, vertices need to be a 2D array containing the x, y coordinates of each vertex.

[drufat]

@rougier I think this pull request for glumpy should fix the issue with the assertion error.
glumpy/glumpy#216

[rougier]

@drufat Oh nice, many thanks.