On Wed, Mar 7, 2012 at 1:26 PM, Nathaniel Smith <n...@pobox.com> wrote:
> On Wed, Mar 7, 2012 at 5:17 PM, Charles R Harris > <charlesr.har...@gmail.com> wrote: > > On Wed, Mar 7, 2012 at 9:35 AM, Pierre Haessig <pierre.haes...@crans.org > > > >> Coming back to Travis proposition "bit-pattern approaches to missing > >> data (*at least* for float64 and int32) need to be implemented.", I > >> wonder what is the amount of extra work to go from nafloat64 to > >> nafloat32/16 ? Is there an hardware support NaN payloads with these > >> smaller floats ? If not, or if it is too complicated, I feel it is > >> acceptable to say "it's too complicated" and fall back to mask. One may > >> have to choose between fancy types and fancy NAs... > > > > I'm in agreement here, and that was a major consideration in making a > > 'masked' implementation first. > > When it comes to "missing data", bitpatterns can do everything that > masks can do, are no more complicated to implement, and have better > performance characteristics. > > Not true. bitpatterns inherently destroys the data, while masks do not. For matplotlib, we can not use bitpatterns because it could over-write user data (or we have to copy the data). I would imagine other extension writers would have similar issues when they need to play around with input data in a safe manner. Also, I doubt that the performance characteristics for strings and integers are the same as it is for masks. Ben Root
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