[Numpy-discussion] feedback request: proposal to add masks to the core ndarray

[Mark Wiebe]

On Fri, Jun 24, 2011 at 10:07 AM, Matthew Brett <matthew.brett at gmail.com>wrote:

> Hi,
>
> On Fri, Jun 24, 2011 at 3:43 PM, Robert Kern <robert.kern at gmail.com>
> wrote:
> > On Fri, Jun 24, 2011 at 09:33, Charles R Harris
> > <charlesr.harris at gmail.com> wrote:
> >>
> >> On Fri, Jun 24, 2011 at 8:06 AM, Robert Kern <robert.kern at gmail.com>
> wrote:
> >
> >>> The alternative proposal would be to add a few new dtypes that are
> >>> NA-aware. E.g. an nafloat64 would reserve a particular NaN value
> >>> (there are lots of different NaN bit patterns, we'd just reserve one)
> >>> that would represent NA. An naint32 would probably reserve the most
> >>> negative int32 value (like R does). Using the NA-aware dtypes signals
> >>> that you are using NA values; there is no need for an additional flag.
> >>
> >> Definitely better names than r-int32. Going this way has the advantage
> of
> >> reducing the friction between R and numpy, and since R has pretty much
> >> become the standard software for statistics that is an important
> >> consideration.
> >
> > I would definitely steal their choices of NA value for naint32 and
> > nafloat64. I have reservations about their string NA value (i.e. 'NA')
> > as anyone doing business in North America and other continents may
> > have issues with that....
>
> It would certainly help me at least if someone (Mark?  sorry to
> ask...) could set out the implementation and API differences that
> would result from the two options:
>
> 1) array.mask option - an integer array of shape array.shape giving
> mask (True, False) values for each element
> 2) nafloat64 option - dtypes with specified dtype-specific missing values
>

That's something that should go in the NEP, I'll email when I update it.

-Mark

>
> Best,
>
> Matthew
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