[SciPy-User] numpy.where() issue

[Oleksandr Huziy]

Just to save you possible frustration later:

'|' is used instead of 'or'

'&' is used instead of 'and'

'~' is used instead of 'not'

Cheers



2015-07-15 14:27 GMT-04:00 Oleksandr Huziy <guziy.sasha at gmail.com>:

> Maybe this way would be clearer (remember parentheses in the condition are
> crucial):
>
> """
> indices = np.where((Yy > 0.02) | (Yy < -0.02))
> """
>
> Cheers
>
>
> 2015-07-15 14:22 GMT-04:00 Sebastian <sebix at sebix.at>:
>
>>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA256
>>
>> Hi,
>>
>> What is this doing? np.where(Yy > 0.02 or Yy < -0.02)
>> Let's split it up
>> (Yy > 0.02) or (Yy < -0.02)
>> The both < > comparisons give boolean numpy arrays, say a and b.
>> a or b
>> The python or-Operator works on boolean values, so it does
>> bool(a) or bool(b)
>> What is "The truth value of an array with more than one element"? It "is
>> ambiguous".
>> Voila
>>
>> You can also use
>> np.logical_or(np.where(...), np.where(...))
>> or shorter
>> np.where(...) | np.where(...)
>>
>> Sebastian
>>
>> On 07/15/2015 08:13 PM, Gabriele Brambilla wrote:
>> > I have problems with numpy.where
>> >
>> > why if I write
>> > deathnote0 = np.where(Yy > 0.02 or Yy < -0.02)
>> > I get:
>> >
>> > Traceback (most recent call last):
>> >
>> >   File "readingK.py", line 63, in <module>
>> >
>> >     deathnote0 = np.where(Yy > 0.02 or Yy < -0.02)
>> >
>> > ValueError: The truth value of an array with more than one element is
>> ambiguous. Use a.any() or a.all()
>> >
>> > while if I do
>> >
>> > deathnote0 = np.where(Yy > 0.02)
>> >
>> > deathnote1 = np.where(Yy < -0.02)
>> >
>> > deathnote = deathnote0 + deathnote1
>> >
>> > it works?
>> >
>> >
>> > thanks
>> >
>> >
>> > Gabriele
>> >
>> >
>> >
>> >
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>> >
>> > --
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>>
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>
>
>
> --
> Sasha
>



-- 
Sasha
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