How to include progressbar with doParallel (previously done only with the doSNOW-package) and foreach loop. Note, that you can easily wrap this into a function.

progressbar_doParallel_foreach.R

library(doParallel)

# Choose number of iterations
n <- 100

# Progress combine function
f <- function(iterator){
  pb <- txtProgressBar(min = 1, max = iterator - 1, style = 3)
  count <- 0
  function(...) {
    count <<- count + length(list(...)) - 1
    setTxtProgressBar(pb, count)
    flush.console()
    cbind(...) # this can feed into .combine option of foreach
  }
}

# Start a cluster
cl <- makeCluster(detectCores(), type='SOCK')
registerDoParallel(cl)

# Run the loop in parallel
result <- foreach(i = icount(n), .combine = f(n)) %dopar% {
  rnorm(10)
}
## Or without the iterators dependency
# result <- foreach(i = 1:n, .combine = f(n)) %dopar% {
#  rnorm(10)
#}


#Stop the cluster
stopCluster(cl)

For me this did not work - the progress bar remained invisible until the very end, when it suddenly reached 100%. See the slow code below:

result <- foreach(i = icount(n), .combine = f(n)) %dopar% {
  mean(rnorm(10000000))
}

Or:

result <- foreach(i = icount(n), .combine = f(n)) %dopar% {
  Sys.sleep(1)
  rnorm(10)
}