# [Scipy-tickets] [SciPy] #1075: Fixing lil_matrix column slicing broke case with sequences for both index arguments.

SciPy Trac scipy-tickets@scipy....
Fri Feb 4 19:35:22 CST 2011

```#1075: Fixing lil_matrix column slicing broke case with sequences for both index
arguments.
--------------------------+-------------------------------------------------
Reporter:  timv          |       Owner:  wnbell
Type:  defect        |      Status:  new
Priority:  high          |   Milestone:  0.9.0
Component:  scipy.sparse  |     Version:  devel
Keywords:                |
--------------------------+-------------------------------------------------
Changes (by warren.weckesser):

* priority:  normal => high

Comment:

Bumping up the priority.  Both lil_matrix and dok_matrix behave
differently compared to a numpy.ndarray and numpy.matrix:
{{{
In [1]: from scipy.sparse import lil_matrix, dok_matrix

In [2]: a = zeros((5,5))   # dense array; numpy's matrix also behaves like
this.

In [3]: a[range(5),range(5)] = -1

In [4]: a
Out[4]:
array([[-1.,  0.,  0.,  0.,  0.],
[ 0., -1.,  0.,  0.,  0.],
[ 0.,  0., -1.,  0.,  0.],
[ 0.,  0.,  0., -1.,  0.],
[ 0.,  0.,  0.,  0., -1.]])

In [5]: b = lil_matrix((5,5))   # sparse LIL matrix.

In [6]: b[range(5),range(5)] = -1

In [7]: b.todense()
Out[7]:
matrix([[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.]])

In [8]: c = dok_matrix((5,5))   # sparse DOK matrix.

In [9]: c[range(5),range(5)] = -1

In [10]: c.todense()
Out[10]:
matrix([[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.],
[-1., -1., -1., -1., -1.]])
}}}

--
Ticket URL: <http://projects.scipy.org/scipy/ticket/1075#comment:1>
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```