hi. i'm trying to understand the difference between using sourceCpp()
and using R CMD compile/shlib. (i seem to get different results using
the different methods.) if that's an FAQ, apologies, but any
enlightenment would be appreciated!
experimenting, i ran into this problem that i haven't seen documented:
if a formal argument to an [[Rcpp::export]] function *begins* with an
underscore. sourceCpp() ends in failure. with the example below,
replacing "_parms" with "parms" makes sourceCpp() happy. in the error
case, the message is:
----
> sourceCpp(code=src)
file15f7e455e0f6f.cpp: In function 'SEXPREC* newRcppMatrixExample(SEXPREC*)':
file15f7e455e0f6f.cpp:40: error: expected `)' before '}' token
file15f7e455e0f6f.cpp:40: error: expected ';' before '}' token
make: *** [file15f7e455e0f6f.o] Error 1
flag-sort -r g++
-I/sw/Library/Frameworks/R.framework/Versions/2.15/Resources/include -DNDEBUG
-I/sw/include -I"/Users/minshall/Library/R/2.15/library/Rcpp/include" -fPIC
-g -O2 -c file15f7e455e0f6f.cpp -o file15f7e455e0f6f.o
Error in sourceCpp(code = src) :
Error 1 occurred building shared library.
----
cheers, Greg
----
#include <algorithm>
#include <Rcpp.h>
#include <cmath>
// [[Rcpp::export]]
SEXP newRcppMatrixExample(SEXP _parms) {
Rcpp::List test(_parms);
try{
Rcpp::NumericMatrix orig(_parms); // creates Rcpp matrix from SEXP
Rcpp::NumericMatrix mat(orig.nrow(), orig.ncol());
// we could query size via
// int n = mat.nrow(), k=mat.ncol();
// and loop over the elements, but using the STL is so much nicer
// so we use a STL transform() algorithm on each element
std::transform(orig.begin(), orig.end(), mat.begin(), sqrt );
return Rcpp::List::create(Rcpp::Named( "result" ) = mat,
Rcpp::Named( "original" ) = orig);
} catch(std::exception& __ex__) {
forward_exception_to_r(__ex__);
} catch(...) {
::Rf_error("c++ exception (unknown reason)");
}
return R_NilValue;
}
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