argparse_help.py

import argparse
import shutil
import textwrap
from itertools import zip_longest


TERMINAL_SIZE = shutil.get_terminal_size(fallback=(80, 60))


def format_two_columns(text1, text2, width1=30, width2=70, left_gutter=2, middle_gutter=2, right_gutter=3):
    terminal_width = min(TERMINAL_SIZE.columns, 100) - (left_gutter + middle_gutter + right_gutter)
    if text2:
        width1 = int(terminal_width * (width1 / (width1 + width2)))
        width2 = int(terminal_width * (width2 / (width1 + width2)))
    else:
        width1 = terminal_width

    wrapped_text1 = textwrap.wrap(text1, width=width1)
    wrapped_text2 = textwrap.wrap(text2, width=width2)

    formatted_lines = [
        f"{' ' * left_gutter}{line1:<{width1}}{' ' * middle_gutter}{line2:<{width2}}{' ' * right_gutter}".rstrip()
        for line1, line2 in zip_longest(wrapped_text1, wrapped_text2, fillvalue="")
    ]

    return "\n".join(formatted_lines) + "\n"


class CustomHelpFormatter(argparse.HelpFormatter):
    def _format_action(self, action):
        help_text = self._expand_help(action) if action.help else ""

        if help_text == "show this help message and exit":
            return ""  # not very useful self-referential humor

        subactions = []
        for subaction in self._iter_indented_subactions(action):
            subactions.append(self._format_action(subaction))

        opts = action.option_strings
        if not opts and not help_text:
            return ""
        elif not opts:  # positional with help text
            opts = [action.dest.upper()]

        if len(opts) == 1:
            left = opts[0]
        elif opts[1].startswith("--no-"):  #  argparse.BooleanOptionalAction
            left = f"{opts[0]} / {opts[1]}"
        elif opts[-1].startswith("--"):
            left = opts[0]
        else:
            left = f"{opts[0]} ({opts[-1]})"

        left += " " + self._format_args(action, "VALUE") + "\n"

        return "".join(subactions) + format_two_columns(left, help_text)


class ArgumentParser(argparse.ArgumentParser):
    def __init__(self, *args, **kwargs):
        kwargs["formatter_class"] = lambda prog: CustomHelpFormatter(prog, max_help_position=40)
        super().__init__(*args, **kwargs)


parser = ArgumentParser()
parser.add_argument('--name', help='help help')
parser.add_argument('--parameter', help='help help')
parser.add_argument('--parameter-name', help='help help')
parser.add_argument('--this-parameter-name', help='help help')
parser.add_argument('--this-is-parameter-name', help='help help')
parser.add_argument('--this-is-a-parameter-name', help='help help')
parser.add_argument('--this-is-a-long-parameter-name', help='help help')
parser.add_argument('--this-is-a-very-long-parameter-name', help='help help')
parser.add_argument('--this-is-a-very-very-long-parameter-name', help='help help')
parser.add_argument('--this-is-a-very-very-very-long-parameter-name', help='help help')

parser.parse_args()

using width1=40, width2=60 (essentially 40% left column, 60% right):

python test.py -h
usage: test.py [-h] [--name NAME] [--parameter PARAMETER] [--parameter-name PARAMETER_NAME] [--this-parameter-name THIS_PARAMETER_NAME] [--this-is-parameter-name THIS_IS_PARAMETER_NAME]
               [--this-is-a-parameter-name THIS_IS_A_PARAMETER_NAME] [--this-is-a-long-parameter-name THIS_IS_A_LONG_PARAMETER_NAME] [--this-is-a-very-long-parameter-name THIS_IS_A_VERY_LONG_PARAMETER_NAME]
               [--this-is-a-very-very-long-parameter-name THIS_IS_A_VERY_VERY_LONG_PARAMETER_NAME] [--this-is-a-very-very-very-long-parameter-name THIS_IS_A_VERY_VERY_VERY_LONG_PARAMETER_NAME]

options:
  --name VALUE                           help help
  --parameter VALUE                      help help
  --parameter-name VALUE                 help help
  --this-parameter-name VALUE            help help
  --this-is-parameter-name VALUE         help help
  --this-is-a-parameter-name VALUE       help help
  --this-is-a-long-parameter-name VALUE  help help
  --this-is-a-very-long-parameter-name   help help
  VALUE
  --this-is-a-very-very-long-parameter-  help help
  name VALUE
  --this-is-a-very-very-very-long-       help help
  parameter-name VALUE