R: Text progress bar in for loop

Question

I have some sample code which contains a for loop and creates some plots like this (my actual data creates several thousands of plots):

xy <- structure(li         


        

Answer 1

for progress bar to work you need a number to track your progress. that is one of the reasons as a general rule I prefer using for with (i in 1:length(ind)) instead of directly putting the object I want there. Alternatively you'll just create another stepi variable that you do stepi = stepi + 1 in every iteration.

you first need to create the progressbar object outside the loop

pb = txtProgressBar(min = 0, max = length(ind), initial = 0) 

then inside you need to update with every iteration

setTxtProgressBar(pb,stepi)

or

setTxtProgressBar(pb,i)

This will work poorly if the loop also has print commands in it

Answer 2

You could write a very simple one on the fly to show percent completed:

n <- 100
for (ii in 1:n) {
  cat(paste0(round(ii / n * 100), '% completed'))
  Sys.sleep(.05)
  if (ii == n) cat(': Done')
  else cat('\014')
}
# 50% completed

Or one to replicate the text bar:

n <- 100
for (ii in 1:n) {
  width <- options()$width
  cat(paste0(rep('=', ii / n * width), collapse = ''))
  Sys.sleep(.05)
  if (ii == n) cat('\014Done')
  else cat('\014')
}
# ============================