Thank you Dirk and also Douglas. This definitely helps. I think I can get this going. Thank you so much for the quick replies.
Best, Stephen On Tue, Aug 7, 2012 at 11:29 AM, Dirk Eddelbuettel <[email protected]> wrote: > > Hi Stephen, > > On 7 August 2012 at 10:55, Stephen J. Barr wrote: > | Greetings, > | > | I am new to Rcpp, RInside and the entire family of related packages. I am > | experienced with R and also C++ using Eigen but I have never combined > the two > | before. > > You are in a good starting position. > > | I would like to create a matrix using R and then play with it using > | Eigen. From what I have read so far, it seems like I can use RInside to > create > | an Rcpp::NumericMatrix. > > That works. Even one of the very oldest examples (rinside_sample1.cpp) does > something related with a Rcpp::NumericMatrix (eg creates one and passes it > around). > > | My question is this: to transform a matrix from a Rcpp::NumericMatrix to > an > | Eigen MatrixXd, do I use RcppEigen? Or is RcppEigen only for calling > C++/Eigen > | from R and not the other way around? > > I think I have an idea as to what you are asking. I think it may help to > step > back for a second and try to imagine the big picture: > > a) Rcpp helps us with the interface defined by .Call: > > SEXP .Call(string somefuncname, SEXP arg1, SEXP arg2, ...) > > so everthing going in and out is a SEXP type. > > b) RInside lets you interchange with an embedded R process, again talking > SEXPs. > > c) Packages like RcppEigen provide wrappers to and from SEXPs. > > So if you don't need a Rcpp::NumericMatrix, don't create one. Create an > Eigen matrix, and use RcppEigen's wrappers to pass it throught the SEXP > interfaces. That should work just fine with RInside as well. > > You will have to expand the RInside Makefile to point to the RcppEigen > headers as well, and then it should just work. > > Hope this helps, Dirk > > > | Thanks, > | Stephen > | > | ---------------------------------------------------------------------- > | _______________________________________________ > | Rcpp-devel mailing list > | [email protected] > | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel > -- > Dirk Eddelbuettel | [email protected] | http://dirk.eddelbuettel.com >
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