[SciPy-user] combine two sparse matrices
Sat May 3 10:24:12 CDT 2008
On Sat, May 3, 2008 at 10:16 AM, Robin <firstname.lastname@example.org> wrote:
> > I was wondering what the most (memory) efficient way of combining two
> > sparse matrices would be.
> I'd still appreciate some advice as to the best way to do this. I
> thought of directly appending to the lists in the lil_matrix, but I
> would then have to sort them again and I wasn't sure if the object
> array could take resizing like this.
If you're worried about speed or memory consumption, then you should
avoid lil_matrix and dok_matrix.
The fastest and most memory efficient approach uses coo_matrix:
row = array([2,3,1,4])
col = array([4,2,3,1])
data = array([5,5,5,5])
A = coo_matrix( (data,(row,col)), shape=(5,5)).tocsr()
The conversion to CSR forces a copy, however CSR and COO are so much
more memory efficient than LIL/DOK that it shouldn't matter.
Nathan Bell email@example.com
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