On Wed, Jun 14, 2017 at 3:59 AM Serguei Sokol <serguei.so...@gmail.com> wrote:
> Le 13/06/2017 à 18:24, Douglas Bates a écrit : > > On Tue, Jun 13, 2017 at 10:56 AM Binxiang Ni <binxian...@gmail.com > <mailto:binxian...@gmail.com>> wrote: > > > > Hi, > > > > I am working on fixing sparse matrix conversion for RcppArmadillo. > Now a problem comes up to me: what kind of sparse matrix is expected to > pass from > > Armadillo to R? That is, what should the result of wrap() be? > dgCMatrix(if logical, lgCMatrix or ngCMatrix) or their original type? > > > > > > What do you mean by "their original type"? > > > > It seems that the correspondence is > > Armadillo Matrix package > > sp_mat <=> dgCMatrix > > sp_cx_mat <=> zgCMatrix > > sp_imat <=> igCMatrix > I would also consider the format used in a package slam. > It simply stores the indexes and non-zero values in a triplet (i,j,v). > That is the format of the dgTMatrix class from the Matrix package for R but not, as far as I can tell, in Armadillo. A brief glance at the Armadillo documentation indicates that sparse matrices are always in the compressed sparse column (CSC) format. I would point out that the sparse matrix facilities in Eigen and RcppEigen are much more extensive than those in Armadillo.
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