An Upcoming Clean Progress Bar in knitr

Yihui Xie 2023-01-05

Do you love the multi-line progress bar when knitting a document? You probably don’t. Neither do I. It’s too verbose and clutters the console with too much information that often has too little real benefit. The information is intended for debugging, but as a debugging champion, you only need to know the error message, right? Why should knitr let you know the information from a hundred other code chunks when the error comes from only one chunk? Worse still, as a programming champion, you never run into errors and always watch the progress bar go from 0% to 100% with a vacant look on your face:

processing file: skeleton.Rmd
  |...                                                       |   4%
   inline R code fragments

  |......                                                    |   9%
label: setup (with options) 
List of 1
 $ include: logi FALSE

  |.........                                                 |  13%
  ordinary text without R code

  |............                                              |  17%
label: unnamed-chunk-1 (with options) 
List of 2
 $ eval: logi FALSE
 $ tidy: logi FALSE

  |...............                                           |  22%
   inline R code fragments


  |..........................................................| 100%
  ordinary text without R code

Why repeating the message “ordinary text without R code” for a hundred times? How dare knitr declare that my text is ordinary? It is extraordinary!!

My apologies to all who have suffered from the meaningless garbage for ten years! The next version of knitr will get rid of the garbage information in the progress bar. The CRAN release may come later this month or next month. For now, you can try the development version:

install.packages('knitr', repos = c(
  yihui = '',
  CRAN = ''
# restart R, and make sure packageVersion('knitr') >= '1.41.8'

Then you should see a single-line progress bar when knitting a document, which only shows the progress and the chunk label by default. The progress bar will be cleaned up afterwards. In case you do want the previous verbose information, you can enable it explicitly via options(knitr.package.verbose = TRUE).

If you don’t like the default text progress bar, you can use your own favorite progress bar by setting the global option (in .Rprofile). For example, you may use winProgressBar on Windows, or progress bars in cli or progressr. See the documentation for more details.

You can use this new option for any purpose of progress tracking. To quote Henrik:

It opens the door to use any combination of progress handlers while knitting, e.g. beepr, cli, progress, txtProgressbar, RStudio, notifier, rpushbullet, shiny, …

With a fresh start of 2023, I hope you will enjoy the fresh progress bar in knitr and make a lot of progress this year.