c_cpp Rcpp min，max

Posted 2021-05-14

// [[Rcpp::plugins(cpp11)]]
#include <Rcpp.h>

using namespace Rcpp;
using std::begin;
using std::end;
using std::next;

// [[Rcpp::export]]
double rcpp_min(NumericVector x) {
    double out = x.at(0);

    for (auto it = next(begin(x)); it != end(x); ++it) {  
        if (*it < out) {
            out = *it;
        }
    }

    return out;
}

// [[Rcpp::export]]
double rcpp_max(NumericVector x) {
    double out = x.at(0);

    for (auto it = next(begin(x)); it != end(x); ++it) {
        if (*it > out) {
            out = *it;
        }
    }

    return out;
}

/*** R
r_vector <- 1:20

rcpp_min(r_vector)
#> [1] 1

rcpp_max(r_vector)
#> 20
*/