Hello,

The code is running very slowly because you are recreating the function in the replicate() loop and because you are creating a data.frame also in the loop.

And because in the bootstrap statistic function med() you are computing the variance of yet another loop. This is probably statistically wrong but like David says, without a problem description it's hard to say.

Also, why compute variances if they are never used?

Here is complete code executing in much less than 2:00 hours. Note that it passes the vector a directly to med(), not a df with just one column.


library(boot)

set.seed(2021)
s <- sample(178:798, 100000, replace = TRUE)
mean(s)

med <- function(d, i) {
  temp <- d[i]
  f <- mean(temp)
  g <- var(temp)
  c(Mean = f, Var = g)
}

N <- 1000
out <- replicate(N, {
  a <- sample(s, size = 5)
  boot.out <- boot(data = a, statistic = med, R = 10000)
  boot.ci(boot.out, type = "stud")$stud[, 4:5]
})
mean(out[1, ] < mean(s) & mean(s) < out[2, ])
#[1] 0.952



Hope this helps,

Rui Barradas

Às 11:45 de 19/12/21, varin sacha via R-help escreveu:
Dear R-experts,

Here below my R code working but really really slowly ! I need 2 hours with my 
computer to finally get an answer ! Is there a way to improve my R code to 
speed it up ? At least to win 1 hour ;=)

Many thanks

########################################################
library(boot)

s<- sample(178:798, 100000, replace=TRUE)
mean(s)

N <- 1000
out <- replicate(N, {
a<- sample(s,size=5)
mean(a)
dat<-data.frame(a)

med<-function(d,i) {
temp<-d[i,]
f<-mean(temp)
g<-var(replicate(50,mean(sample(temp,replace=T))))
return(c(f,g))

}

   boot.out <- boot(data = dat, statistic = med, R = 10000)
   boot.ci(boot.out, type = "stud")$stud[, 4:5]
})
mean(out[1,] < mean(s) & mean(s) < out[2,])
########################################################

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and provide commented, minimal, self-contained, reproducible code.

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