Dear list,
I want to do some operations on an array, here exemplified by taking log (the
operations I have in mind are made using RcppArmadillo):
> pp <- array(c(.1, .4, .4, .1), dim=c(2,2),dimnames=list(A=c("a1","a2"),
> B=c("b1","b2")))
> log(pp)
B
A b1 b2
a1 -2.3025851 -0.9162907
a2 -0.9162907 -2.3025851
It is essential that dim and dimnames attributes are preserved. My take on this
task is:
src <-'
using namespace arma;
using namespace Rcpp;
NumericVector p(pp_);
// Some computations using RcppArmadillo
vec pp = as<vec>(pp_);
vec aa = log(pp);
// Get the result back
NumericVector ans(p.length());
ans = aa;
// Set attributes
ans.attr("dim") = p.attr("dim");
ans.attr("dimnames") = p.attr("dimnames");
return(wrap(ans));
'
> library(inline)
> loga <- cxxfunction(signature(pp_ = ""), src, plugin = "RcppArmadillo",
> verbose=F)
> loga(pp)
B
A b1 b2
a1 -2.3025851 -0.9162907
a2 -0.9162907 -2.3025851
This works, but if anyone can spot a more elegant (fewer lines) way of doing
it, I would be happy to know...
Best regards
Søren
_______________________________________________
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
