r - Simplest way to do parallel replicate

Question

I am fond of the parallel package in R and how easy and intuitive it is to do parallel versions of apply, sapply, etc.

Is there a similar parallel function for replicate?

Answer 1

You can just use the parallel versions of lapply or sapply, instead of saying to replicate this expression n times you do the apply on 1:n and instead of giving an expression, you wrap that expression in a function that ignores the argument sent to it.

possibly something like:

#create cluster
library(parallel)
cl <- makeCluster(detectCores()-1)  
# get library support needed to run the code
clusterEvalQ(cl,library(MASS))
# put objects in place that might be needed for the code
myData <- data.frame(x=1:10, y=rnorm(10))
clusterExport(cl,c("myData"))
# Set a different seed on each member of the cluster (just in case)
clusterSetRNGStream(cl)
#... then parallel replicate...
parSapply(cl, 1:10000, function(i,...) { x <- rnorm(10); mean(x)/sd(x) } )
#stop the cluster
stopCluster(cl)

as the parallel equivalent of:

replicate(10000, {x <- rnorm(10); mean(x)/sd(x) } )