using purrr for simple R simulations

simu_purrr.R

nrep <- 100
d <- expand.grid(n=c(3,5,10,20), sd=c(1,2,3))
d <- d[rep(seq_len(nrow(d)),each=nrep),]

simulate <- function(n, sd) {
  rnorm(n=n, mean=0, sd=sd)
}

library(purrr)
library(dplyr)

d2 <- d %>% mutate(
  sim = map2(n, sd, simulate),
  RMSE = map_dbl(sim, ~sqrt(mean(.^2))),
  MAD = map_dbl(sim, ~1.48*median(abs(.)))
)

d2 <- select(d2, -sim)
d2$n %<>% factor

library(reshape)
m <- melt(d2, id.vars=c("n","sd"))

library(ggplot2)
p <- ggplot(m, aes(x=n, y=value, col=variable)) + 
  geom_boxplot() +
  facet_wrap(~ sd)
print(p)