Thank you Romain! All clear now!
Best Simon On Jun 7, 2013, at 1:13 PM, Romain Francois <rom...@r-enthusiasts.com> wrote: > Le 07/06/13 13:09, Simon Zehnder a écrit : >> HI Dirk, hi Romain, >> >> allright, this is now clear to me, if I want to reuse memory, the allocated >> memory from R (so implicitly in C) must of course have the same type - >> otherwise the memory has a different size. > > so far, this is obvious. > >> On the other side I then assume, that the Rcpp:as<class M>() function makes >> a cast and therefore creates a copy with new allocated memory of the type >> included in M? Therefore a reuse of memory with this function is not >> possible. > > Depends what is M, but most of the time yes, as<> copies data. > >> Best >> >> Simon >> >> >> On Jun 6, 2013, at 8:31 PM, Dirk Eddelbuettel <e...@debian.org> wrote: >> >>> >>> On 6 June 2013 at 13:17, Dirk Eddelbuettel wrote: >>> | >>> | On 6 June 2013 at 19:05, Simon Zehnder wrote: >>> | | sorry I had overseen this message from you. Okay, so the explicit cast >>> to SEXP together with the assignment operator makes the deal. But it still >>> includes the reuse of memory right, i.e. the '=' does not call the copy >>> constructor? >>> | >>> | But how could an _unsigned int_ from Armadillo possibly have the same >>> value >>> | as a _signed int_ in R? >>> | >>> | Either you are efficient (no copy), or you are correct (with a copy). I do >>> | not see how you could have both. >>> >>> Sorry -- please ignore this message. >>> >>> I had mistakenly assumed that you were still thinking about arma::umat to >>> integer. For direct int-to-int this is indeed efficient just like the >>> double-to-double is for arma::mat to NumericMatrix (and dito for vectors). >>> I >>> though that was a given -- maybe need to make this (even) more explicit in >>> the documentation. >>> >>> So in sum: you get correct and efficient behaviour if and only if you stick >>> with the types natively supported in Armadillo and R. >>> >>> Dirk >>> >>> -- >>> Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com >> >> > > > -- > Romain Francois > Professional R Enthusiast > +33(0) 6 28 91 30 30 > > R Graph Gallery: http://gallery.r-enthusiasts.com > > blog: http://blog.r-enthusiasts.com > |- http://bit.ly/Zs97qg : highlight 0.4.1 > `- http://bit.ly/10X94UM : Mobile version of the graph gallery > _______________________________________________ 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
