rcpp-speed.R

library(Rcpp)
library(microbenchmark)

cppFunction(
  'int looped_sum(int x, const int num_loops) {
        for(int i = 0; i < num_loops; i++) {
          x = x + 1;
        }
        return x;
    }')

looped_sum_R <- function(x, num_loops) {
  for(i in 1L:num_loops) {
    x <- x + 1L
  }
  x
}

microbenchmark(
  looped_sum(0L, 50000000L),
  looped_sum_R(0L, 50000000L),
  times = 10
)
#> Unit: microseconds
#>                         expr         min          lq         mean
#>    looped_sum(0L, 50000000L)       1.188       1.536     111.1451
#>  looped_sum_R(0L, 50000000L) 1138032.985 1152609.126 1259103.4133
#>       median          uq         max neval
#>       13.735      23.507     988.772    10
#>  1176141.634 1363335.973 1627560.344    10

#' Created on 2018-02-18 by the [reprex package](http://reprex.tidyverse.org) (v0.1.1.9000).