Can I get argparse not to repeat the argument indication after the two option names?

Question

When I specify a parameter for argparse with both a short and long name, e.g.:

parser.add_argument("-m", "--min", dest="min_value", type=float, help="Minimum value")

and ask for --help, I get:

  -m MIN_VALUE, --min MIN_VALUE
                        Minimum value

This annoys me. I would like MIN_VALUE not to be repeated. So, for example:

  [-m | --min-value] MIN_VALUE
                        Minimum value

can I get argparse to print that (other than by overriding the --help message entirely)?

Answer 1

You don't have to override the help message, just create your own HelpFormatter class:

import argparse


class MyFormatter(argparse.HelpFormatter):
    def _format_action_invocation(self, action):
        if not action.option_strings:
            (metavar,) = self._metavar_formatter(action, action.dest)(1)
            return metavar
        else:
            parts = []

            if action.nargs == 0:
                parts.extend(action.option_strings)
            else:
                default = action.dest.upper()
                args_string = self._format_args(action, default)
                parts.extend([f'[{" | ".join(action.option_strings)}] {args_string}']) # Customize the format here

            return " ".join(parts)

# Example usage
parser = argparse.ArgumentParser(formatter_class=MyFormatter)

This way you can adjust the structure of the arguments printed within the help message without having to completely change it.