[Numpy-discussion] Behavior of nan{max, min} and nanarg{max, min} for all-nan slices.

josef.pktd at gmail.com josef.pktd at gmail.com
Wed Oct 2 12:56:19 EDT 2013

On Wed, Oct 2, 2013 at 12:37 PM, Stéfan van der Walt <stefan at sun.ac.za> wrote:
> On 2 Oct 2013 18:04, "Charles R Harris" <charlesr.harris at gmail.com> wrote:
>> The question is what to do when all-nan slices are encountered in the
>> nan{max,min} and nanarg{max, min} functions. Currently in 1.8.0, the first
>> returns nan and raises a warning, the second returns intp.min and raises a
>> warning. It is proposed that the nanarg{max, min} functions, and possibly
>> the nan{max, min} also, raise an error instead.
> I agree with Nathan; this sounds like more reasonable behaviour to me.

If I understand what you are proposing

-1 on raising an error with nan{max, min},

an empty array is empty in all columns
an array with nans, might be empty in only some columns.

as far as I understand, nan{max, min} only make sense with arrays that
can hold a nan, so we can return nans.

If a user calls with ints or bool, then there are either no nans or
the array is empty, and I don't care.

with nanarg{max, min} I would just return 0 in an all nan column,
since the max or min is nan, and one is at zero.
(but I'm not arguing)


> Stéfan
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