Re: [Pysparse-users] Adding a column of a sparse matrix to a dense vector

[gorkiana m. <gor...@gm...>]

Dominique,

Yes, I noticed that, I also made some changes because it asked numerix which
was inside Fipy. Thank you. But yet I could not use it.

Nevertheless I managed to solve my problem during this weekend.

Basically pysparse.spmatrix.ll_mat objects have two methods: keys() and
values()

With this two it is possible to do what I want. This is what I did:

A = pysparse.spmatrix.ll_mat(10,10)   # a 10 x 10 sparse matrix
X = numpy.arange(0,10)                       # a dense vector of length 10

A[0,1] = 10; A[0,2] = 10; A[0,3] = 10

To add the first row of A to X one just needs to do the following:

A_indices = numpy.array(A[0,:].keys())[:,1]     # keys is a list of tuples,
so converting to numpy.array yelds a matrix
                                                                         #
the first column is the row index and the second column the column index
                                                                         #
we just need the column index
                                                                         #
we get a vector with the indices where A has nonzero values at row 0
A_values = numpy.array(A[0,:].values())         # the nonzero values of row
0

X[A_indices] = X[A_indices] + A_values

Simple!

Thank you very much Dominique and Daniel for your help. Probably I will have
more looks at FiPy because I will have more problems for sure!

-artur palha

On Sat, Jun 21, 2008 at 2:58 PM, Dominique Orban <dom...@gm...>
wrote:

> Artur,
>
> On top of the file that Daniel sent, you also need sparseMatrix.py
> which you can download from the repository Daniel mentioned earlier. I
> also attach it below.
>
> Good luck,
> Dominique
>
> On Fri, Jun 20, 2008 at 10:09 AM, Daniel Wheeler
> <dan...@gm...> wrote:
> > On Fri, Jun 20, 2008 at 6:50 AM, Artur Palha <art...@gm...>
> wrote:
> >> Thank you for your help Daniel
> >
> > No problem.
> >
> >> I have downloaded it but it is asking for more modules from your
> project.
> >
> > Yes. I realized that Dominique Orban created a version of this that
> > works with pysparse alone. See attachment. It really needs to be
> > integrated into pysparse properly. I just haven't had a chance yet.
> >
> >> I will try to have a look and see if I can do something based on what
> >> you did. In the meantime I will also have a look a pyTrilinos.
> >
> > Try scipy as well.
> >
> > --
> > Daniel Wheeler
> >
> > -------------------------------------------------------------------------
> > Check out the new SourceForge.net Marketplace.
> > It's the best place to buy or sell services for
> > just about anything Open Source.
> > http://sourceforge.net/services/buy/index.php
> > _______________________________________________
> > Pysparse-users mailing list
> > Pys...@li...
> > https://lists.sourceforge.net/lists/listinfo/pysparse-users
> >
> >
>