On Sat, Jun 25, 2011 at 8:52 AM, Matthew Brett <[email protected]>wrote:
> Hi, > > On Sat, Jun 25, 2011 at 3:46 PM, Charles R Harris > <[email protected]> wrote: > > > > > > On Sat, Jun 25, 2011 at 8:31 AM, Matthew Brett <[email protected]> > > wrote: > >> > >> Hi, > >> > >> On Sat, Jun 25, 2011 at 3:21 PM, Charles R Harris > >> <[email protected]> wrote: > >> > > >> > > >> > On Sat, Jun 25, 2011 at 5:29 AM, Pierre GM <[email protected]> > wrote: > >> >> > >> >> This thread is getting quite long, innit ? > >> >> And I think it's getting a tad confusing, because we're mixing two > >> >> different concepts: missing values and masks. > >> >> There should be support for missing values in numpy.core, I think we > >> >> all > >> >> agree on that. > >> >> * What's been suggested of adding new dtypes (nafloat, naint) is > great, > >> >> by > >> >> why not making it the default, then ? > >> >> > >> >> * Operations involving a NA (whatever the NA actually is, depending > on > >> >> the > >> >> dtype of the input) should result in a NA (whatever the NA defined by > >> >> the > >> >> outputs dtype). That could be done by overloading the existing ufuncs > >> >> to > >> >> support the new dtypes. > >> >> * There should be some simple methods to retrieve the location of > those > >> >> NAs in an array. Whether we just output the indices or a full boolean > >> >> array > >> >> (w/ True for a NA, False for a non-NA or vice-versa) needs to be > >> >> decided. > >> >> * We can always re-implement masked arrays to use these NAs in a way > >> >> which > >> >> would be consistent with numpy.ma (so as not to confuse existing > users > >> >> of > >> >> numpy.ma): a mask would be a boolean array with the same shape than > the > >> >> underlying ndarray, with True for NA. > >> >> Mark, I'd suggest you modify your proposal, making it clearer that > it's > >> >> not to add all of numpy.ma functionalities in the core, but just > >> >> support > >> >> these missing values. Using the term 'mask' should be avoided as much > >> >> as > >> >> possible, use a 'missing data' or whatever. > >> > > >> > I think he aims to support both. > >> > >> I don't think Mark is proposing to support both. He's proposing to > >> implement only array.mask. > >> > > > > I think you are confusing function with implementation. If you look at > the > > current NEP, it does NA but does so by using masks behind the scene in a > > transparent manner. > > Yes, there is some confusion; just to be clear, I'm pointing out that > Mark is not proposing to implement na-dtypes, and is proposing to > implement array.mask. > > I would say he is proposing to implement na-dtypes by means of masks. Chuck
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