Peter Otten <__pete...@web.de> wrote:
>John Ladasky wrote:
>
>> On Friday, January 17, 2014 6:16:28 PM UTC-8, duncan smith wrote:
>>
>>> >>> a = np.arange(10)
>>> >>> c = np.where((2 < a) & (a < 7))
>>> >>> c
>>> (array([3, 4, 5, 6]),)
>>
>> Nice! Thanks!
>>
>> Now, why does the multiple comparison fail, if you happen to know?
>
>2 < a < 7
>
>is equivalent to
>
>2 < a and a < 7
>
>Unlike `&` `and` cannot be overridden (*),,,,
And just in case it isn't obvious to the original poster, the expression "2
< a" only works because the numpy.array class has an override for the "<"
operator. Python natively has no idea how to compare an integer to a
numpy.array object.
Similarly, (2 < a) & (a > 7) works because numpy.array has an override for
the "&" operator. So, that expression is compiled as
numpy.array.__and__(
numpy.array.__lt__(2, a),
numpy.array.__lt__(a, 7)
)
As Peter said, there's no way to override the "and" operator.
--
Tim Roberts, t...@probo.com
Providenza & Boekelheide, Inc.
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