R_compiler.R

install.packages("rbenchmark")
library(compiler)
library(rbenchmark)

enableJIT(level = 3)
#enableJIT(level = 0)

my_mean = function(x) {
  total = 0
  n = length(x)
  for(i in 1:n)
    total = total + x[i]/n
  total
}

cmp_mean = cmpfun(my_mean)

x = rnorm(100)
benchmark(my_mean(x), cmp_mean(x), mean(x), 
          columns=c("test", "elapsed", "relative"),
          order="relative", replications=5000)