jfinkels / birkhoff Goto Github PK

For the latest version of numpy (1.19.0 at 2022.7), the code can not get a result. I check the code, and find that the line 62 in the birkhoff.py ( print(list(zip(*(matches.items())))) ) seems don't work correctly.

When replace the "list" with "tuple", it works well. (The line 62 is "print(tuple(zip(*(matches.items()))))").

Running on Fedora 27

pip3 install nose networkx birkhoff numpy --user

Run the test_birkhoff_von_neumann_decomposition() function with the following result

>>> test.test_birkhoff_von_neumann_decomposition()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/tbottom/test.py", line 55, in test_birkhoff_von_neumann_decomposition
    actual = birkhoff_von_neumann_decomposition(D)
  File "/home/tbottom/.local/lib/python3.6/site-packages/birkhoff/decompose.py", line 173, in birkhoff_von_neumann_decomposition
    M = hopcroft_karp_matching(G)
  File "/home/tbottom/.local/lib/python3.6/site-packages/birkhoff/matching.py", line 98, in hopcroft_karp_matching
    left, right = bipartite_sets(G)
  File "/home/tbottom/.local/lib/python3.6/site-packages/networkx/algorithms/bipartite/basic.py", line 203, in sets
    raise nx.AmbiguousSolution(msg)
networkx.exception.AmbiguousSolution: Disconnected graph: Ambiguous solution for bipartite sets.

Hi,
Currently I'm using you birkhoff module, it works fine in most cases, great work!

However, in the to_permutation_matrix(matches) functions, the length of matches might be different from the input matrix S(D) 's degree (m,n) (Somehow? I'm not sure about the algorithm itself.In the test, sometimes it works fine but sometimes failed), leading to a index_out_of_range exception, since you are using len(matches) as the length of returned matrix P.

After I create the right length of P in to_permutation_matrix(), it works.