Hi,

How do I delete a row or a column from a sparse matrix?

I can construct a new matrix by concatenating two sub matrices, but I think it would be costly:

viewtopic.php?f=74&t=106944

Do you really need to have it before suppressing it? Perhaps it's better to not insert it or if you want to remove several ones, maybe a using a permutation matrix would do a better job?

If your matrix is column major you can still remove columns efficiently by first pruning the entries with SparseMatrix::prune(...), then play with the internal structure to copy the outer pointers of the remaining columns from j+1 to j (see the outerIndexPtr() function), and finally call conservative resize to remove the last empty one.

I'll consider these options; thanks.