[Numpy-discussion] Equality not working as expected with ndarray sub-class

[Frédéric Bastien]

Hi,

__array__priority wasn't checked for ==, !=, <, <=, >, >= operation. I
added it in the development version and someone else back-ported it to the
1.7.X branch.

So this will work with the next release of numpy.

I don't know of a workaround until the next release.

Fred


On Thu, Jul 4, 2013 at 9:06 AM, Thomas Robitaille <
thomas.robitaille at gmail.com> wrote:

> Hi everyone,
>
> The following example:
>
>     import numpy as np
>
>     class SimpleArray(np.ndarray):
>
>         __array_priority__ = 10000
>
>         def __new__(cls, input_array, info=None):
>             return np.asarray(input_array).view(cls)
>
>         def __eq__(self, other):
>             return False
>
>     a = SimpleArray(10)
>     print (np.int64(10) == a)
>     print (a == np.int64(10))
>
> gives the following output
>
>     $ python2.7 eq.py
>     True
>     False
>
> so that in the first case, SimpleArray.__eq__ is not called. Is this a
> bug, and if so, can anyone think of a workaround? If this is expected
> behavior, how do I ensure SimpleArray.__eq__ gets called in both
> cases?
>
> Thanks,
> Tom
>
> ps: cross-posting to stackoverflow
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