[Numpy-discussion] comparing arrays with NaN in them.

Christopher Barker Chris.Barker@noaa....
Fri Aug 24 11:53:51 CDT 2007


Timothy Hochberg wrote:
> in principle it's not safe to rely on NaNs being bitwise equal.

Thanks Tim, I always learn a lot on this list.

Anyway, I think my suggestion of "binary equal" wasn't really what I 
want. What I want is essentially a NaN-safe comparison, much like the 
NaN-safe functions like nanmax, nanmin, etc.

I guess what that would involve is looping through the arrays, checking 
for "==", then checking if both are NaN if it returns false. (or 
checking for the NaN's first).

I'm not sure NaNifying the other comparisons would make any sense: NaN > 
NaN (and all the other comparison's would have to return False anyway.

So, would a nanequal function be useful? would it be hard to write?

-Chris

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