On Fr, 2014-08-29 at 22:10 -0400, Benjamin Root wrote:
Consider the following:
a = np.array([(1, 'a'), (2, 'b'), (3, 'c')], dtype=[('foo', 'i'), ('bar', 'a1')])
b = np.append(a, (4, 'd')) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/ben/miniconda/lib/python2.7/site-packages/numpy/lib/function_base.py", line 3555, in append return concatenate((arr, values), axis=axis) TypeError: invalid type promotion b = np.insert(a, 4, (4, 'd')) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/ben/miniconda/lib/python2.7/site-packages/numpy/lib/function_base.py", line 3464, in insert new[slobj] = values ValueError: could not convert string to float: d
Ooops, nice bug in there, might have been me :) (will open a PR). - Sebastian
In my original code snippet I was developing which has a more involved dtype, I actually got a different exception: b = np.append(a, c) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/ben/miniconda/lib/python2.7/site-packages/numpy/lib/function_base.py", line 3553, in append values = ravel(values) File "/home/ben/miniconda/lib/python2.7/site-packages/numpy/core/fromnumeric.py", line 1367, in ravel return asarray(a).ravel(order) File "/home/ben/miniconda/lib/python2.7/site-packages/numpy/core/numeric.py", line 460, in asarray return array(a, dtype, copy=False, order=order) ValueError: setting an array element with a sequence.
Luckily, this works as a work-around:
b = np.append(a, np.array([(4, 'd')], dtype=a.dtype)) b array([(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd')], dtype=[('foo', 'i'), ('bar', 'S1')])
The same happens whether I enclose the value with square bracket or not. I suspect that this array type just wasn't considered when its checking logic was developed. This is with 1.8.2 from miniconda. Should we consider this a bug or are structured arrays just not expected to be modified like this?
Cheers!
Ben Root
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