[Numpy-discussion] missing data discussion round 2

Lluís xscript@gmx....
Wed Jun 29 13:20:57 CDT 2011


Mark Wiebe writes:

> There seems to be a general idea that masks and NA bit patterns imply
> particular differing semantics, something which I think is simply
> false.

Well, my example contained a difference (the need for the "skipna=True"
argument) precisely because it seemed that there was some need for
different defaults.

Honestly, I think this difference breaks the POLA (principle of least
astonishment).


[...]
> As far as I can tell, the only required difference between them is
> that NA bit patterns must destroy the data. Nothing else. Everything
> on top of that is a choice of API and interface mechanisms. I want
> them to behave exactly the same except for that necessary difference,
> so that it will be possible to use the *exact same Python code* with
> either approach.

I completely agree. What I'd suggest is a global and/or per-object
"ndarray.flags.skipna" for people like me that just want to ignore these
entries without caring about setting it on each operaion (or the other
way around, depends on the default behaviour).

The downside is that it adds yet another tweaking knob, which is not
desirable...


Lluis

-- 
 "And it's much the same thing with knowledge, for whenever you learn
 something new, the whole world becomes that much richer."
 -- The Princess of Pure Reason, as told by Norton Juster in The Phantom
 Tollbooth


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