On Fri, Jan 24, 2014 at 11:30 AM, Emanuele Olivetti emanuele@relativita.com wrote:

Hi,

I just came across this unexpected behaviour when creating a np.array() from two other np.arrays of different shape. Have a look at this example:

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import numpy as np a = np.zeros(3) b = np.zeros((2,3)) c = np.zeros((3,2)) ab = np.array([a, b]) print ab.shape, ab.dtype ac = np.array([a, c], dtype=np.object) print ac.shape, ac.dtype ac_no_dtype = np.array([a, c]) print ac_no_dtype.shape, ac_no_dtype.dtype

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The output, with NumPy v1.6.1 (Ubuntu 12.04) is:

(2,) object (2, 3) object Traceback (most recent call last): File "/tmp/numpy_bug.py", line 9, in <module> ac_no_dtype = np.array([a, c]) ValueError: setting an array element with a sequence.

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The result for 'ab' is what I expect. The one for 'ac' is a bit surprising. The one for ac_no_dtype even is more surprising.

Is this an expected behaviour?

the exception in ac_no_dtype is what I always expected, since it's not a rectangular array. It usually happened when I make a mistake. **Unfortunately** in newer numpy version it will also create an object array.

AFAIR

Josef

Best,

Emanuele

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