[Numpy-discussion] list as array item and casting problem problem

Gen-Nan Chen gnchen@gmail....
Wed Nov 14 17:38:34 CST 2007


Hi! All,
I have below strange behavior in numpy. Can anyone shed some light on this:

I have an array with each item as a list object. You will get this when you
use scipy.sparse

In [369]: k
Out[369]: array([[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]],
dtype=object)


Assigning value by using slicing is working
In [370]: k[0:3] = [[i+3] for i in range(3)]

In [371]: k
Out[371]: array([[3], [4], [5], [3], [4], [5], [6], [7], [8], [9]],
dtype=object)


But assigning value by using a list for slicing is NOT


In [374]: k[[0, 1,2]] = [[i+3] for i in range(3)]

In [375]: k
Out[375]: array([3, 4, 5, [3], [4], [5], [6], [7], [8], [9]], dtype=object)


You can see those list objects casted to integer.

Is this a bug or a feature? if I want to slice it with random index without
casting it, what should I do?

-- 
Gen-Nan Chen, Ph. D.
email: gnchen@gmail.com
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