[Numpy-discussion] assignment to matrix slice in Numeric bug/feature?

[Roman Suzi]

hello,

I've found that the following fragment of code gives an error while with
other shapes of b there is no problem:

----------------------------
#!/usr/bin/python2

from Numeric import *
from Matrix import *
a = Matrix(zeros([4,4]))
b = Matrix(ones([2,1]))
print a, a.shape
print b, b.shape
q = a[1:3,1:2]
print q, q.shape
a[1:3,1:2] = b
-----------------------------

resulting in:
-------------------------------------
Matrix([[0, 0, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 0]]) (4, 4)
Matrix([[1],
       [1]]) (2, 1)
Matrix([[0],
       [0]]) (2, 1)
Traceback (most recent call last):
  File "./numpybug.py", line 11, in ?
    a[1:3,1:2] = b
  File "/usr/lib/python2.1/site-packages/Numeric/Matrix.py", line 180, in 
__setitem__
    def __setitem__(self, index, value): self.array[index] = 
asarray(squeeze(value),self._typecode)
ValueError: matrices are not aligned for copy
-----------------------------------------------

The mentioned behaviour looks like a bug, because
a[1:3,1:2] and b have the same shape and according to docs
b must be copied to a-slice 1:1...

Numeric is version 21.0, Python 2.1 under Linux RedHat 7.2.

Thank you in advance!

Sincerely yours, Roman Suzi
-- 
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