Convert std::vector to Rcpp matrix

Question

This is an Rcpp conversion related Q. I\'m looking to convert a long std::vector into a Rcpp matrix object, but want to know if there is an easy conversion format. Naturally

Answer 1

You chose a good approach. In the OpenMP context, you have to stay away from the single-threaded R. So std::vector is good.

And yes, we have constructors from std::vector to Rcpp::NumericVector and Rcpp::NumericMatrix (which is after all just a vector with a dimensions attribute) as well as the Rcoo:Integer* variants, as well as the usual as<> and wrap converters.

There should be plenty of examples in the Rcpp unit tests, the Rcpp examples, and of course on the Rcpp Gallery site.

Edit: Here is an overly simple example:

 R> cppFunction('NumericVector phil(int n) { std::vector x(n);
 +              return wrap(x); }') 
 R> phil(4)  
 [1] 0 0 0 0    
 R>