[Numpy-discussion] What should be the value of nansum of nan's?
Warren Weckesser
warren.weckesser@enthought....
Wed Apr 28 11:22:16 CDT 2010
Travis Oliphant wrote:
>
> On Apr 26, 2010, at 12:03 PM, Charles R Harris wrote:
>
>>
>>
>> On Mon, Apr 26, 2010 at 10:55 AM, Charles R Harris
>> <charlesr.harris@gmail.com <mailto:charlesr.harris@gmail.com>> wrote:
>>
>> Hi All,
>>
>> We need to make a decision for ticket #1123
>> <http://projects.scipy.org/numpy/ticket/1123#comment:11>
>> regarding what nansum should return when all values are nan. At
>> some earlier point it was zero, but currently it is nan, in fact
>> it is nan whatever the operation is. That is consistent, simple
>> and serves to mark the array or axis as containing all nans. I
>> would like to close the ticket and am a bit inclined to go with
>> the current behaviour although there is an argument to be made
>> for returning 0 for the nansum case. Thoughts?
>>
>>
>> To add a bit of context, one could argue that the results should be
>> consistent with the equivalent operations on empty arrays and always
>> be non-nan.
>>
>> In [1]: nansum([])
>> Out[1]: nan
>>
>> In [2]: sum([])
>> Out[2]: 0.0
>
>
> I favor nansum([]) returning 0.0 which implies returning 0.0 when all
> the elements are nan.
>
+1
> -Travis
>
>
>
>
>
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