Transform a boost::array into NumericVector in Rcpp

Question

In my C++ script (run in R using Rcpp), I defined :

typedef boost::array< double ,3 > state_type;

Now, I want to create a function to tra

Answer 1

How about

Rcpp::NumericVector boost_array_to_nvec(state_type const& s) {
    Rcpp::NumericVector nvec(s.size());
    for (size_t i = 0; i < s.size(); ++i) {
        nvec[i] = s[i];
    }
    return nvec;
}
state_type nvec_to_boost_array(Rcpp::NumericVector const& nvec) {
    state_type s;
    for (size_t i = 0; i < s.size(); ++i) {
        s[i] = nvec[i];
    }
    return s;
}
...
state_type s {0,0,0};
Rcpp::NumericVector nvec = boost_array_to_nvec(s);
s = nvec_to_boost_array(nvec);

If you have to do this a lot of times. This might not be the most efficient way of doing the transformation. But now you have to look that nvec is already allocated to the correct size.

void boost_array_to_nvec(state_type const& s, Rcpp::NumericVector& nvec) {
    for (size_t i = 0; i < s.size(); ++i) {
        nvec[i] = s[i];
    }
}
void nvec_to_boost_array (Rcpp::NumericVector const& nvec, state_type& s) {
    for (size_t i = 0; i < s.size(); ++i) {
        s[i] = nvec[i];
    }
}
...
state_type s {0,0,0};
Rcpp::NumericVector nv(3);
boost_array_to_nvec(s, nv);
nvec_to_boost_array(nv, s);