[Numpy-discussion] What should be the value of nansum of nan's?

Keith Goodman kwgoodman@gmail....
Wed Apr 28 11:28:39 CDT 2010

On Mon, Apr 26, 2010 at 9:55 AM, Charles R Harris
<charlesr.harris@gmail.com> wrote:
> Hi All,
> We need to make a decision for ticket #1123 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?

I use nansum a lot because I treat NaNs as missing data. I think a lot
of people use NaNs as missing data but few admit it. My packages have
grown to depend on nansum([nan, nan]) returning NaN. I vote to keep
the current behavior. Changing nansum([]) to return zero, however, has
no impact on me.

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