How do you create a progress bar when using the “foreach()” function in R?

Question

there are some informative posts on how to create a counter for loops in an R program. However, how do you create a similar function when using the parallelized version wit

Answer 1

You can also get this to work with the progress package.

# loading parallel and doSNOW package and creating cluster ----------------
library(parallel)
library(doSNOW)

numCores<-detectCores()
cl <- makeCluster(numCores)
registerDoSNOW(cl)

# progress bar ------------------------------------------------------------
library(progress)

iterations <- 100                               # used for the foreach loop  

pb <- progress_bar$new(
  format = "letter = :letter [:bar] :elapsed | eta: :eta",
  total = iterations,    # 100 
  width = 60)

progress_letter <- rep(LETTERS[1:10], 10)  # token reported in progress bar

# allowing progress bar to be used in foreach -----------------------------
progress <- function(n){
  pb$tick(tokens = list(letter = progress_letter[n]))
} 

opts <- list(progress = progress)

# foreach loop ------------------------------------------------------------
library(foreach)

foreach(i = 1:iterations, .combine = rbind, .options.snow = opts) %dopar% {
  summary(rnorm(1e6))[3]
}

stopCluster(cl)