Julia 0.4 will have both compressed sparse column as well as compressed sparse row sparse matrices. We should probably write some iterators to work with cases such as these too. They will be convenient to use for sure, but may not give the best performance.
-viral On Monday, July 21, 2014 12:15:46 PM UTC+5:30, Florian Oswald wrote: > > Transposing is fine! Thanks for that! > > On Sunday, 20 July 2014, Odd Andersen <[email protected]> wrote: > >> Sparse matrices in Julia are to my understanding stored as compressed >> sparse columns. So it is very easy to get the nonzero elements for a given >> column, but not so easy for rows. >> >> To get the indices of nonzeros rows for column 'c' in sparse matrix M, >> one can use (at least in the current implementation): >> >> M.rowval[a.colptr[col] : M.colptr[col+1]-1] >> >> To do the same by rows would be more complicated (a quick-and-dirty >> solution would of course be to transpose your matrix first). >> I am however not a Julia expert, so perhaps there's a solution I am not >> aware of. >> >>
