[Numpy-discussion] Adding an axis argument to numpy.unique

josef.pktd@gmai... josef.pktd@gmai...
Tue Aug 20 06:49:56 CDT 2013


On Tue, Aug 20, 2013 at 7:47 AM,  <josef.pktd@gmail.com> wrote:
> On Tue, Aug 20, 2013 at 7:34 AM, Nathaniel Smith <njs@pobox.com> wrote:
>> On 20 Aug 2013 12:09, <josef.pktd@gmail.com> wrote:
>>>
>>> On Tue, Aug 20, 2013 at 5:04 AM, Nathaniel Smith <njs@pobox.com> wrote:
>>> > On 20 Aug 2013 01:39, "Joe Kington" <joferkington@gmail.com> wrote:
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> ...<snip>
>>> >>>
>>> >>>
>>> >>> However, my first interpretation of an axis argument in unique would
>>> >>> be that it treats each column (or whatever along axis) separately.
>>> >>> Analogously to max, argmax and similar.
>>> >>
>>> >>
>>> >> Good point!
>>> >>
>>> >> That's certainly a potential source of confusion.  However, I can't
>>> >> seem
>>> >> to come up with a better name for the kwarg. Matlab's "unique" function
>>> >> has
>>> >> a "rows" option, which is probably a more intuitive name, but doesn't
>>> >> imply
>>> >> the expansion to N-dimensions.
>>> >>
>>> >> "axis" is still fairly idiomatic, despite the confusion over "unique
>>> >> rows/columns/etc" vs "unique items within each row/column/etc".
>>> >>
>>> >> Any thoughts on a better name for the argument?
>>> >
>>> > I also found this pretty confusing when first looking at the PR.
>>> >
>>> > One option might be to invert the sense of the argument to emphasize
>>> > that
>>> > it's treating subarrays as units, so instead of specifying the iteration
>>> > axis you specify the axes of the subarray. compare_axis= or something?
>>>
>>> you would need compare_axes (plural for ndim>2) and have to specify
>>> all but one axis, AFAICS.
>>
>> Well, it makes sense to specify any arbitrary subset of axes, whether or not
>> that's currently implemented.
>
> not AFAICS, if you want to return a rectangular array without
> nans/missing values.

and unless you want to ravel() the remaining axis, which is also weird
(I think).

Josef

>
> Josef
>
>>
>> -n
>>
>>
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