Hi, On Sat, Jun 25, 2011 at 4:05 PM, Charles R Harris <[email protected]> wrote: > > > 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.
But that would be confusing function with implementation. array.mask is the implementation with an extra mask array. na-dtypes is the implementation with values in the array set to special missing values. See you, Matthew _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
