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

there informative posts on how create counter loops in r program. however, how create similar function when using parallelized version "foreach()"?

edit: after update dosnow package has become quite simple display nice progress bar when using %dopar% , works on linux, windows , os x

dosnow officially supports progress bars via .options.snow argument.

library(dosnow) cl <- makecluster(2) registerdosnow(cl) iterations <- 100 pb <- txtprogressbar(max = iterations, style = 3) progress <- function(n) settxtprogressbar(pb, n) opts <- list(progress = progress) result <- foreach(i = 1:iterations, .combine = rbind,                    .options.snow = opts) %dopar% {     s <- summary(rnorm(1e6))[3]     return(s) } close(pb) stopcluster(cl)  

yet way of tracking progress, if keep in mind total number of iterations, set .verbose = t print console iterations have been finished.

previous solution linux , os x

on ubuntu 14.04 (64 bit) , os x (el capitan) progress bar displayed when using %dopar% if in makecluster function oufile = "" set. not seem work under windows. on makecluster:

outfile: direct stdout , stderr connection output workers. "" indicates no redirection (which may useful workers on local machine). defaults ‘/dev/null’ (‘nul:’ on windows).

example code:

library(foreach) library(dosnow) cl <- makecluster(4, outfile="") # number of cores. notice 'outfile' registerdosnow(cl) iterations <- 100 pb <- txtprogressbar(min = 1, max = iterations, style = 3) result <- foreach(i = 1:iterations, .combine = rbind) %dopar%  {       s <- summary(rnorm(1e6))[3]       settxtprogressbar(pb, i)        return(s) } close(pb) stopcluster(cl)  

this progress bar looks like. looks little odd since new bar printed every progression of bar , because worker may lag bit causes progress bar go , forth occasionally.