[Numpy-discussion] Numpy where

[John Kirkham]

Hey Everyone,

I felt like I should add to the mix. I added the issue ( https://github.com/numpy/numpy/issues/5679 ) to tie these options together. My main concern is that both wheres behave the same.
As far as using a scalar as the first argument, it was an easy example. We could have used actual arrays and we would have had arrays full of Nones.
Though I do see this point of "why should we have indices returned for a scalar". This means nonzero should change, as well.
I agree with Chuck on case 4. If we already allow all other scalars, None should be no different. Plus, I would rather have a breaking change in the ma module than in core.

Best,
John



>> > I think the question is if scalars should be acceptable for the first
>> > argument, not if it should be for the 2nd and 3rd argument.
>> > 
>> > If scalar can be given for the first argument, the the first three makes
>> > sense. Although, I have no clue why we would allow that.
>> > 
>> > Ben Root
>> > On Mar 12, 2015 9:25 PM, "Nathaniel Smith" <njs at pobox.com> wrote:
>> 
>> > On Mar 12, 2015 5:02 PM, "Charles R Harris" <charlesr.harris at gmail.com>
>> > wrote:
>> > >
>> > > Hi All,
>> > >
>> > > This is apropos gh-5582 dealing with some corner cases of np.where. The
>> > following are the current behavior
>> > >
>> > > >>> import numpy
>> > > >>> numpy.where(True)  # case 1
>> > > ... (array([0]),)
>> > > >>> numpy.where(True, None, None)  # case 2
>> > > ... array(None, dtype=object)
>> > > >>> numpy.ma.where(True)  # case 3
>> > > ... (array([0]),)
>> > > >>> numpy.ma.where(True, None, None)  # case 4
>> > > ... (array([0]),)
>> > >
>> > > The question is, what exactly should be done in these cases? I'd be
>> > inclined to raise an error for cases 1 and 3. Case two looks correct to me
>> > if we agree that scalar inputs are acceptable. Case 4 looks wrong.
>> >
>> > I can't think of any reason scalars wouldn't be acceptable. So everything
>> > you suggest sounds right to me.
>> >
>> > -n
>> > Hi All,
>> >
>> > This is apropos gh-5582 <https://github.com/numpy/numpy/pull/5582>
>> > dealing with some corner cases of np.where. The following are the current
>> > behavior
>> >
>> > >>> import numpy
>> > >>> numpy.where(True)  # case 1
>> > ... (array([0]),)
>> > >>> numpy.where(True, None, None)  # case 2
>> > ... array(None, dtype=object)
>> > >>> numpy.ma.where(True)  # case 3
>> > ... (array([0]),)
>> > >>> numpy.ma.where(True, None, None)  # case 4
>> > ... (array([0]),)
>> >
>> > The question is, what exactly should be done in these cases? I'd be
>> > inclined to raise an error for cases 1 and 3. Case two looks correct to me
>> > if we agree that scalar inputs are acceptable. Case 4 looks wrong.
>> >
>> > Thoughts?
>> >
>> > Chuck
>> >
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>> >
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>> >
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