That is great example of why folks should NOT use the .C() interface.
Rcpp can help here, __even if you do not use any Rcpp language features__.
Below is a showcase for the recent sourceCpp() function which takes a C++
file (shown below), converts it and optionally runs the embedded R
code. Think of as something like Sweave for mixing C++ and R rather than
Latex and R.
Source file is shown via cat on the cmdline:
edd@max:/tmp$ cat dblvec.cpp
#include <Rcpp.h>
#include <vector>
// [[Rcpp::export]]
std::vector<double> dbl(std::vector<double> x) {
std::vector<double> y(x.size());
for (unsigned int i=0; i<y.size(); i++)
y[i] = 2.0*x[i];
return y;
}
/*** R
myx <- seq(1.1, 5.5, by=1.1)
print(dbl(myx))
***/
edd@max:/tmp$
edd@max:/tmp$
We then simply source it to show off how it transform a C++ vector of doubles:
edd@max:/tmp$ R --quiet -e 'library(Rcpp); sourceCpp("dblvec.cpp")'
R> library(Rcpp); sourceCpp("dblvec.cpp")
R> myx <- seq(1.1, 5.5, by = 1.1)
R> print(dbl(myx))
[1] 2.2 4.4 6.6 8.8 11.0
R>
R>
edd@max:/tmp$
No make, compiler invocation, linking, ... which all happen behind the
scenes. We just enjoy the C++ function to double the content of a double
vector.
Hope this helps, Dirk
--
Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
