[Numpy-discussion] Any and all NaNs

Robert Kern robert.kern@gmail....
Fri May 23 13:44:14 CDT 2008

On Fri, May 23, 2008 at 12:22 PM, Keith Goodman <kwgoodman@gmail.com> wrote:

> But the first example
>>> x = mp.matrix([[mp.nan]])
>>> x
>   matrix([[ NaN]])
>>> x.all()
>   True
>>> x.any()
>   True
> is still surprising.

On non-boolean arrays, .all() and .any() check each element to see if
it is not equal to 0. NaN != 0. Returning False would be just as
wrong. If there were a Maybe in addition to True and False, then
perhaps that would be worth changing, but I don't see a reason to
change the rule as it is.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
 -- Umberto Eco

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