Copy one sparse matrix into another in Python

Copying Xf into features. In this case, Xf is a scipy.sparse.csr_matrix and features is a dok_matrix.

        nz_indices = Xf.nonzero()
        for ix, jx in zip(nz_indices[0], nz_indices[1]):
            features[ix, jx] = Xf[ix, jx]

Notes: 

1. When I checked, the assignment of a 0 to an element of a dok_matrix resulted in a crash. So 0 assignments have to be avoided. 

Python

I am trying to run matplotlib but seems it is not installed on my windows (ActivePython 2.6) package. Therefore I was looking for a good way to install it. Now, it is a part of several scientific libraries and these libraries have different installers.

One good way to install is using easy_install, but it looks not possible for python 2.6. Finally I gave up on easy_install. I downloaded the matplotlib library (for python 2.5 as there is none corresponding to 2.6).

Finally I concluded that there is little support for python 2.6 and I uninstalled the 2.6 version and installed the 2.5 version.