[Numpy-discussion] Properties of ma.masked singleton
alexander.belopolsky at gmail.com
Fri Jan 6 08:27:15 CST 2006
In the current numpy version ma.masked singleton has the following
which is a change from old MA, where
It changes shape when filled:
and so on.
The code contains numerous "if x is masked" statements to support all
I would like to suggest a somewhat radical change for your review.
There are two main uses of ma.masked:
1. To set mask:
>>> x = ma.zeros(5)
>>> x[2:4] = ma.masked
>>> print x
[0 0 -- -- 0]
2. To check if an element is masked:
>>> x is ma.masked
The second property allows a cute looking idiom "x[i] is masked", but
only works for single element access:
>>> x[2:4] is ma.masked
It also leads to strange results:
My proposal is to eliminate the property #2 from ma and redefine
masked as None. Single element getitem will return a rank zero
MaskedArray. We can also add "is_masked" property, which will allow a
convenient check in the form "x[i].is_masked".
The main benefit of this proposal is that x[i] will be duck typing
compatible with numpy scalars.
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