[Numpy-discussion] Re: take for character arrays?
Faheem Mitha
faheem at email.unc.edu
Thu Apr 15 10:07:15 CDT 2004
On Thu, 15 Apr 2004 05:13:29 +0000 (UTC), Faheem Mitha
<faheem at email.unc.edu> wrote:
> Hi,
>
> I'm trying to extract subarrays of a character array using take(), but
> getting mysterious errors, for example:
>
> ValueError: Invalid destination array: partial indices require
> contiguous non-byteswapped destination
>
> I am thinking that perhaps this operation is not supported for
> character arrays, and I should convert my character array to a numeric
> array instead (the strings are all of length 1).
I read this again and realised this does not give any specific
information, and is not very coherent. Got to avoid those late night
postings. So here are the details. If I set axis = 0 there is no
problem. I also don't have this problem with numerical arrays.
I am sure there is a simple reason for this, and hopefully a simple
workaround.
Thanks in advance.
Faheem.
**************************************************************************
In [22]: import numarray.strings as str
In [23]: import numarray
In [24]: s = str.array(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
'i'],shape=(3,3))
In [25]: numarray.take(s,(1,2),axis=1)
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
/home/faheem/wc/corrmodel/boost/<console>
/usr/lib/python2.3/site-packages/numarray/ufunc.py in take(array,
indices, axis, outarr, clipmode)
1779 raise ValueError("indices must be a sequence")
1780 work = _gen.swapaxes(array, 0, axis)
-> 1781 work = work._take((indices,), outarr=outarr,
clipmode=clipmode)
1782 return _gen.swapaxes(work, 0, axis)
1783 else:
/usr/lib/python2.3/site-packages/numarray/generic.py in _take(self,
indices, **keywds)
795 def _take(self, indices, **keywds):
796 indices = list(indices)
--> 797 impliedShape, N = _takeShape(self, indices)
798 result = self._clone(shape=impliedShape)
799 indices = self._fix_pt_indices(indices)
/usr/lib/python2.3/site-packages/numarray/generic.py in
_takeShape(scattered, indexArrays)
133 nShape = scattered._shape[-leftOver:]
134 if scattered.isbyteswapped() or not
scattered.iscontiguous():
--> 135 raise ValueError("Invalid destination array:
partial indices require contiguous non-byteswapped destination")
136 else:
137 N = scattered._itemsize
ValueError: Invalid destination array: partial indices require
contiguous non-byteswapped destination
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