[Numpy-discussion] the mean, var, std of empty arrays

Olivier Delalleau shish@keba...
Wed Nov 21 20:22:17 CST 2012


Current behavior looks sensible to me. I personally would prefer no warning
but I think it makes sense to have one as it can be helpful to detect
issues faster.

-=- Olivier

2012/11/21 Charles R Harris <charlesr.harris@gmail.com>

> What should be the value of the mean, var, and std of empty arrays?
> Currently
>
> In [12]: a
> Out[12]: array([], dtype=int64)
>
> In [13]: a.mean()
> Out[13]: nan
>
> In [14]: a.std()
> Out[14]: nan
>
> In [15]: a.var()
> Out[15]: nan
>
> I think the nan comes from 0/0. All of these also raise warnings the first
> time they are called.
>
> Chuck
>
>
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