How can I implement matlabs ``ismember()`` command in Python?

Question

here is my problem: I would like to create a boolean matrix B that contains True everywhere that matrix A has a value contained in vector v. One inconvenient so

Answer 1

Alas, setmember1d as it exists in numpy is broken when either array has duplicated elements (as A does here). Download this version, call it e.g sem.py somewhere on your sys.path, add to it a first line import numpy as nm, and THEN this finally works:

>>> import sem
>>> print sem.setmember1d(A.reshape(A.size), v).reshape(A.shape)
[[False True True]
 [True True False]
 [True False False]]

Note the difference wrt @Aants' similar answer: this version has the second row of the resulting bool array correct, while his version (using the setmember1d that comes as part of numpy) incorrectly has the second row as all Trues.