Thx Sergei, Yes you're right, I want to use my c++ function as a R function. Sorry about the Banana function that takes 2 scalars, you’re right again, it should take a vector as input. Please ignore this for now (this is a dummy example)
My c++ "Banana" function is already compiled in my project by the time I start he R session (via RInside). I can pass it to R via a XPtr. Something like R["myfuncptr"] = Rcpp::XPtr<func_type>(new func_type (Banana)); So, in R I got "myfuncptr" which is an "externalptr". Now my only problem is to make that "externalptr" seen as a R function in R. Maybe with something like a ".Call(externalptr, param...)"? Here (https://stackoverflow.com/questions/13904786/r-pointer-to-c-function), Romains says something about wrapping the external pointer into an R function... But I struggle to find the correct way to achieve this with the function parameters... Thank you William -----Message d'origine----- De : Serguei Sokol <serguei.so...@gmail.com> Envoyé : mardi 12 novembre 2019 17:49 À : LEVRA-JUILLET William <william.levra-juil...@addactis.com>; rcpp-devel@lists.r-forge.r-project.org Objet : Re: [Rcpp-devel] RInside: C/C++ function(s) passed to R? Le 08/11/2019 à 11:06, LEVRA-JUILLET William a écrit : > Hi all, > > I’m evaluating RInside/Rcpp to interact our C++ project with R. > > I’ve seen the samples to get/set data (matrix, dataframes, etc) > to/from R and it builds/works fine. > > (Using gcc/mingw compiler from RTools on Windows) > > My questions is about functions… > > My project is C++, and it uses RInside to call R from our code. > > Let’s say I have a C++ function implemented in my project, and I want > to pass that c++ function to R so it can be “used” as a R function > (typically passed as argument to optim/optimize) > > I couldn’t find a way to do that using RInside. > > Ideally, I’d like to achieve something like: > > #include <RInside.h> > > double Banana(double x, double y) > > { > > return (1-x)*(1-x)+100*(y-x*x)*(y-x*x); > > } > > Int main() > > { > > RInside R(argc,, argv); > > R[“fn”] = Banana; > > R.parseEval(“optim(c(-2,-2), fn”); > > } > > I believe it’s similar to > https://stackoverflow.com/questions/53729493/rinside-wrapping-a-c-func > tion-for-use-in-an-r-function > > But I can’t really understand the Rcpp::XPtr suggestion from Dirk. > > Any help or pointers welcome J Sorry for a late comment but for what it's worth, XPtr won't help here as optim() expects an R function, not C++ pointer to a function. Moreover, this R function takes only one argument -- a vector, not a couple of scalars. So maybe you meant something similar to: #include <RInside.h> int main(int argc, char *argv[]) { RInside R(argc, argv); R.parseEval("Rcpp::cppFunction('double Banana(double x, double y) {return (1-x)*(1-x)+100*(y-x*x)*(y-x*x);};', cacheDir='lib')"); R.parseEval("fn <- function(p, ...) Banana(p[1L], p[2L])"); Rcpp::RObject res = R.parseEval("optim(c(-2,-2), fn)"); Rf_PrintValue(res); return 0; } which prints: $par [1] 0.9990277 0.9977136 $value [1] 1.269722e-05 $counts function gradient 157 NA $convergence [1] 0 $message NULL As already underlined by others this is a sub-optimal way to use C++ functions in R but here it is imposed by optim() interface. For better designed interfaces (at least from "optimality of R/C++ exchanges" point of view) refer to examples cited by Dirk and Inaki. Best, Serguei. > > Thx a mil > > mailbox:///home/sokol/.thunderbird/r8hre4b3.default/Mail/pop.insa-tlse > .fr/Inbox?number=44&header=quotebody&part=1.1.2&filename=image005.jpg > <https://addactis.letsignit.com/r/32/6de77c22-c065-4906-899e-eec38189d > 60a/undefined> > > mailbox:///home/sokol/.thunderbird/r8hre4b3.default/Mail/pop.insa-tlse > .fr/Inbox?number=44&header=quotebody&part=1.1.3&filename=image006.png > <https://addactis.letsignit.com/r/199/c042c4a7-2508-4bf6-801a-4eeb0977 > 8ade/undefined> > mailbox:///home/sokol/.thunderbird/r8hre4b3.default/Mail/pop.insa-tlse > .fr/Inbox?number=44&header=quotebody&part=1.1.4&filename=image007.png > <https://addactis.letsignit.com/r/42/b8791eba-0dab-4aa1-ab9d-813a5f8be > 48d/undefined> > mailbox:///home/sokol/.thunderbird/r8hre4b3.default/Mail/pop.insa-tlse > .fr/Inbox?number=44&header=quotebody&part=1.1.5&filename=image008.png > <https://addactis.letsignit.com/r/45/15ea361f-f441-4b13-94a0-4bdb30820 > d9a/undefined> > > > > > * William **LEVRA-JUILLET* > Senior Software Architect > * ADDACTIS Software* > +33 (0)4 81 92 13 00 > > > www.addactis.com > <https://addactis.letsignit.com/r/32/91871b88-8586-4561-b012-50a3a7925 > 27a/undefined> > > <https://addactis.letsignit.com/r/32/cf8ac9eb-d46f-4524-bc9e-5cdb532be > f11/undefined> > > <https://addactis.letsignit.com/r/199/49e483e9-091d-4caf-a1b4-7e37d9c9 > ac9e/undefined> > <https://addactis.letsignit.com/r/42/72f7499f-cd02-4bd4-835a-88f1053ca > bf2/undefined> > <https://addactis.letsignit.com/r/45/b9ce1c50-1455-48cb-b90f-b8348d799 > 476/undefined> > > > > > * William **LEVRA-JUILLET* > Senior Software Architect > * ADDACTIS Software* > +33 (0)4 81 92 13 00 > > > www.addactis.com > <https://addactis.letsignit.com/r/32/9cd210c2-e7cd-4d30-995a-e3ba4da16 > 780/undefined> > > > _______________________________________________ > Rcpp-devel mailing list > Rcpp-devel@lists.r-forge.r-project.org > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-deve > l > _______________________________________________ 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
