On 14 June 2017 at 20:44, Dmitriy Selivanov wrote: | My 2 cents. Last couple of years I used sparse matrices a lot. Matrix package | is really great. I'm not sure I understand issue with wrapping - as Doug said | CSC format is main in both Armadillo and Matrix. Given matrix in CSC format | (dgCMatrix/CsparseMatrix) it is trivial to convert it to COO or CSR with as(x, | "TsparseMatrix") / as(x, "RsparseMatrix"). | | Second point is about slam package and COO format. I didn't use it, but used | scipy, Armadillo, Eigen. And none of these packages use COO format for | operations on matrices... I doubt it could be efficient. | | Third point is that I have feeling that nowadays CSR format is more mainstream. | For instance Eigen implements multithreaded sparse - dense multiplications and | sparse solvers (https://eigen.tuxfamily.org/dox/TopicMultiThreading.html). Same | story about sparse BLAS with Intel MKL - it works with CSR matrices. I realize | that CSR = transposed CSC, but still it is not convenient to transpose mind | each time. (Would be great to add more support for CSR matrices, but this is | out of scope of this discussion).
Really nice summary, and very helpful because ... | And last my observation - I agree with Doug that it seems that Eigen has much | stronger support for operations with sparse matrices. ... this year we have Binxiang trying to get (Rcpp)Armadillo closer to (Rcpp)Eigen in terms of sparse matrix support. It is a valid goal because many of really like Armadillo yet have more needs for sparse matrix support with Armadillo and eg MLPACK or other things built on top of Armadillo. I also want to add that the load-time critique with respect to Matrix hits more on whether S4 is a good or bad idea (and for something as complex and feature-rich as Matrix it is almost certainly a good one) and has little to do with the representation of sparse matrix indices. Dirk PS Please consider removing quoted text. This message I am replying to exceeded the size limit so I had to manually approve it (and I also incremented the limit from the old, small default, but still...) -- http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
