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

[Pierre GM]

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.
_______________________________________________
NumPy-Discussion mailing list
NumPy-Discussion@scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion