Progress bars in purrr

purrr's map functions have a .progress argument that you can use to create a progress bar. .progress can be:

• FALSE, the default: does not create a progress bar.

• TRUE: creates a basic unnamed progress bar.

• A string: creates a basic progress bar with the given name.

• A named list of progress bar parameters, as described below.

It's good practice to name your progress bars, to make it clear what calculation or process they belong to. We recommend keeping the names under 20 characters, so the whole progress bar fits comfortably even on on narrower displays.

Progress bar parameters

• clear: whether to remove the progress bar from the screen after termination. Defaults to TRUE.

• format: format string. This overrides the default format string of the progress bar type. It must be given for the custom type. Format strings may contain R expressions to evaluate in braces. They support cli pluralization, and styling and they can contain special progress variables.

• format_done: format string for successful termination. By default the same as format.

• format_failed: format string for unsuccessful termination. By default the same as format.

• name: progress bar name. This is by default the empty string and it is displayed at the beginning of the progress bar.

• show_after: numeric scalar. Only show the progress bar after this number of seconds. It overrides the cli.progress_show_after global option.

• type: progress bar type. Currently supported types are:

  • iterator: the default, a for loop or a mapping function,

  • tasks: a (typically small) number of tasks,

  • download: download of one file,

  • custom: custom type, format must not be NULL for this type. The default display is different for each progress bar type.

Further documentation

purrr's progress bars are powered by cli, so see Introduction to progress bars in cli and Advanced cli progress bars for more details.