Convert Rcpp Numeric Vector into boost:ublas:vector

I'm trying to convert from an rtype object to ublas from boost.

Using some code I found from the Rcpp dev list regarding ublas, I'm able to return the ublas vector wrapped as an rtype.

e.g.

// Converts from ublas to rtype

template <typename T>   
Rcpp::Vector< Rcpp::traits::r_sexptype_traits<T>::rtype >
ublas2rcpp( const boost::numeric::ublas::vector<T>& x ){
  return Rcpp::Vector< Rcpp::traits::r_sexptype_traits<T>::rtype >(
      x.begin(), x.end()
  ) ;
}

To mimick the behavior import behavior, I currently use a loop over ublas vector of the corresponding length and just assign everything from the rtype to it.

Would switching from a loop improve performance?

// My attempt to convert from rtype to ublas

// so R can find the libraries
//[[Rcpp::depends(BH)]]
//[[Rcpp::plugins("cpp11")]]

#include <Rcpp.h>


#include <cstdlib>
#include <iostream>
#include <fstream>


#include <boost/numeric/odeint.hpp>
#include <boost/numeric/ublas/matrix.hpp>
#include <boost/numeric/ublas/io.hpp>

using namespace std;
using namespace Rcpp;
using namespace boost::numeric::ublas;

typedef boost::numeric::ublas::vector< double > vector_type;
typedef boost::numeric::ublas::matrix< double > matrix_type;

template <typename T>    /// this need to be fixed up, hopefully working for now though
Rcpp::Vector< Rcpp::traits::r_sexptype_traits<T>::rtype >
ublas2rcpp( const boost::numeric::ublas::vector<T>& x ){
  return Rcpp::Vector< Rcpp::traits::r_sexptype_traits<T>::rtype >(
      x.begin(), x.end()
  ) ;
}

// [[Rcpp::export]]
NumericVector main(NumericVector x1)
{


  int L =x1.length();


  vector_type x(L , 0 ); // initialize the vector to all zero

  for(int i=0;i<L;i++)
  {

    x(i) =  x1(i);

  }


return(ublas2rcpp(x));   

}