[Numpy-discussion] missing data discussion round 2
Thu Jun 30 10:07:58 CDT 2011
On Wed, Jun 29, 2011 at 1:20 PM, Lluís <email@example.com> wrote:
> 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
> > 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
One way around this would be to create an ndarray subclass which changes
that default. Currently this would not be possible to do nicely, but with
the _numpy_ufunc_ idea I proposed in a separate thread a while back, this
> "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
> NumPy-Discussion mailing list
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