[Numpy-discussion] new MaskedArray class

[Marten van Kerkwijk]

Hi Eric,

The easiest definitely is for the mask to just propagate, which that even
if just one point is masked, all points in the fft will be masked.

On the direct point I made, I think it is correct that since one can think
of the Fourier transform of a sine/cosine fit, then there is a solution
even in the presence of some masked data, and this solution is distinct
from that for a specific choice of fill value. But of course it is also
true that the solution will be at least partially degenerate in its result
and possibly indeterminate (e.g., for the extreme example of a real
transform for which all but the first point are masked, all cosine term
amplitudes are equal to the value of the first term, and are completely
degenerate with each other, and all sine term amplitudes are indeterminate;
one has only one piece of information, after all). Yet the inverse of any
of those choices reproduces the input. That said, clearly there is a choice
to be made whether this solution is at all interesting, which means that
you are right that it needs an explicit user decision.

All the best,

Marten
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