[Numpy-discussion] MaskedArray and the min, max, sum, prod Methods
Fri Jan 4 14:20:11 CST 2008
On Friday 04 January 2008 12:01:14 Alexander Michael wrote:
> Concretely, this is how I would write my own prod function:
> def ma_prod(a):
> p = 1.0
> for x in a.data[~a.mask]:
> p *= x
> return p
Which would work only in 1D, as you mentioned.
> All the CS mumbo-jumbo aside, the real question appears to be are fully
> masked arrays empty or undefined? I would consider them conceptually empty,
> if only because it makes for a convenient continuity as the number of
> masked elements increases from one to the whole of the array.
That's a way to see it. Personally, I'm happy with this behavior: getting
masked as the result of .sum() tells me that all the initial values were
masked, which is not the same thing as getting 0.
> Thanks for the hard work on the new MaskedArray. I'm attempting to be
> constructive by raising these issues, so please let me know if my comments
> are otherwise.
Oh please, thanks a lot for your contributions ! Another issue is that we need
to ensure compatibility with the previous version of maskedarray
(numpy.core.ma). At the end, that's what matters.
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