[Numpy-discussion] return type of ndarray + ma.array

Alexander Belopolsky alexander.belopolsky at gmail.com
Thu Jan 5 20:51:09 CST 2006


the following session demonstrates the difference between numpy.ma  
and old MA behavior.

Sum ndarray and ma.array is ndarray

 >>> type(numeric.array([1])+ma.array([1]))
<type 'numpy.ndarray'>

However, taken in the different order,
 >>> type(ma.array([1])+numeric.array([1]))
<class 'numpy.core.ma.MaskedArray'>

In the old MA module the sum is MaskedArray in any order:
 >>> type(MA.array([1])+Numeric.array([1]))
<class 'MA.MaskedArray'>

 >>> type(Numeric.array([1])+MA.array([1]))
<class 'MA.MaskedArray'>

I suspected that new ma module may not have __radd__ defined, but it  
does.

Can anyone explain this?

Thanks.

-- sasha

PS:

 >>> import numpy
 >>> numpy.__version__
'0.9.3.1831'





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