[Numpy-discussion] Summing an array with dtype=object

Pierre GM pgmdevlist at gmail.com
Mon Nov 16 00:11:43 EST 2009

An issue was recently raised about summing a MaskedArray with a np.object dtype. Turns out that the problem is numpy based:
Let's sum using integers
>>> type(np.sum([1,2,3], dtype=np.int32))
<type 'numpy.int32'>

Now, with a np.object dtype:
>>>  type(np.sum([1,2,3],dtype=object))
 <type 'int'>

And we no longer have a np.object, but a regular Python int. Which, unfortunately for MaskedArray, does not have a view object (hence the bug).
Is it the expected behavior ?

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