Benchmarking returning zero filled rcpp vs rextendr vector and matrix.

rcpp_vs_rust_zeros.R

# compare rcpp and rust zero matrices performance to test wrap times.

library(microbenchmark)


Rcpp::sourceCpp(
  code = '
#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
IntegerVector rcpp_zeros_intvec(int n) {
    IntegerVector my_vec(n);
    return my_vec;
}

// [[Rcpp::export]]
IntegerMatrix rcpp_zeros_intmat(int n) {
    IntegerMatrix my_mat(n, n);
    return my_mat;
}

// [[Rcpp::export]]
IntegerVector rcpp_zeros_intvec_dimmed(int n) {
    IntegerVector my_vec(n * n);
    my_vec.attr("dim") = Dimension(n, n);
    return my_vec;
}
')

rextendr::rust_source(
  profile = "release",
  extendr_deps = list(
    `extendr-api` = list(git = "https://github.com/extendr/extendr")
  ),
  code = '
/// @export
#[extendr]
fn rust_zeros_intvec(n: i32) -> Robj {
    let my_vec = vec!(0; n as usize);
    r!(my_vec)
}

/// @export
#[extendr]
fn rust_zeros_intmat(n: i32) -> Robj {
    let my_mat = RMatrix::new_matrix(n as usize, n as usize, |_, _| 0);
    r!(my_mat)
}

/// @export
#[extendr]
fn rust_zeros_intmat_viavec(n: i32) -> Robj {
    let my_vec = vec!(0; n as usize * n as usize);
    let my_mat: RMatrix<i32> = r!(my_vec).as_matrix().unwrap();
    r!(my_mat)
}

extendr_module! {
    mod rust_wrap;
    fn rust_zeros_intvec;
    fn rust_zeros_intmat;
    fn rust_zeros_intmat_viavec;
}
')

cat("\n************ integer vector\n")
cat("cpp and rust all.equal? ")
print(all.equal(rcpp_zeros_intvec(100), rust_zeros_intvec(100)))

cat("\n************ integer matrix direct\n")
cat("cpp and rust all.equal? ")
print(all.equal(rcpp_zeros_intmat(100), rust_zeros_intmat(100)))

cat("\n************ integer matrix via vec\n")
cat("cpp and rust all.equal? ")
cat("No rust solution to compare to yet.")


cat("\n************ microbench results\n")
for (N in cumprod(c(10, rep(2, 6)))) {
  cat("N = ", N, "\n")
  mb_ziv_out <- microbenchmark(rcpp_zeros_intvec(N), rust_zeros_intvec(N),
                               rcpp_zeros_intmat(N), rust_zeros_intmat(N),
                               rcpp_zeros_intvec_dimmed(N), times=1000)
  print(mb_ziv_out)
}