Just to clarify this (for myself): In a broader perspective, isn't it so now that there is very limited need for as< >(some_SEXP)?
When calling from R we can declare input to be NumericMatrices, NumericVectors ets, but we can also declare it to be arma-matrices, arma-vectors etc AND also Eigen-matrices etc? Where one definitely needs as< >() is when inputting some SEXP which one wants to coerce to some STL container? Are there other cases where one definitely needs the coercion via as<>()?? Cheers Søren -----Original Message----- From: Dirk Eddelbuettel [mailto:[email protected]] Sent: 3. februar 2014 20:20 To: Douglas Bates Cc: Dirk Eddelbuettel; French, Joshua; Søren Højsgaard; [email protected] Subject: Re: [Rcpp-devel] Sparse matrix operations On 3 February 2014 at 12:59, Douglas Bates wrote: | On Mon, Feb 3, 2014 at 11:48 AM, Dirk Eddelbuettel <[email protected]> wrote: | | | On 3 February 2014 at 10:23, French, Joshua wrote: | | Soren and Doug, | | | | Thanks for the info about the sparse matrices. I'll give it a go and | seen what | | happens. If it works out, then perhaps I'll be able to provide a nice | | RcppGallery example. | | Yes -- there isn't much yet in RcppArmadillo but this is expected to | grow. And CRAN now has rARPACK so we get cheaply to the object code too. | | One last comment I should have made earlier: "dense" data from R comes over | cheaply as a SEXP; "sparse" will always require a copy. Keep that in | mind, | and on the margin don't believe anything any of us say but keep profiling | and | measuring :) | | | Not really. RcppEigen offers conversion of SEXPs to | Eigen::SparseMatrix and Eigen::MappedSparseMatrix types. The second | uses the storage from R without copying and hence should generally be declared with the const modifier. Oooops. My bad. I guess I generalized from my less performing converters contributed to RcppArmadillo. Time permitting, maybe I should have another look at RcppEigen and see if I can do better for RcppArmadillo. | I think that wonderful vignetter by Bates and Eddelbuettel describes | this :-) :-) Dirk -- Dirk Eddelbuettel | [email protected] | http://dirk.eddelbuettel.com _______________________________________________ Rcpp-devel mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
