[SciPy-User] Fancy indexing bug in sparse.lil_matrix?
Tony S Yu
tonyyu at MIT.EDU
Fri Apr 2 15:13:19 EDT 2010
The scipy tutorial suggests that lil_matrix supports fancy indexing, but that doesn't seem to be completely true:
>>> from scipy import sparse
>>>
>>> N = 5
>>> A_lil = sparse.eye(N, N, format='lil')
>>> idx = range(N)
>>> print A_lil[idx, idx].todense()
[[ 1. 1. 1. 1. 1.]]
>>> A_lil[idx, idx] = 5
>>> print A_lil.todense()
[[ 5. 5. 5. 5. 5.]
[ 5. 5. 5. 5. 5.]
[ 5. 5. 5. 5. 5.]
[ 5. 5. 5. 5. 5.]
[ 5. 5. 5. 5. 5.]]
In the above code, getting the main diagonal works as expected, but setting the main diagonal produces unexpected results. Is this a known issue?
This issue doesn't seem to be the same as Ticket #1064 (plus, I believe that issue is fixed in my version of scipy).
-Tony
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