pythonbooleanargparsecommand-line-arguments

Parsing boolean values with argparse

I would like to use argparse to parse boolean command-line arguments written as "--foo True" or "--foo False". For example:

my_program --my_boolean_flag False

However, the following test code does not do what I would like:

import argparse
parser = argparse.ArgumentParser(description="My parser")
parser.add_argument("--my_bool", type=bool)
cmd_line = ["--my_bool", "False"]
parsed_args = parser.parse(cmd_line)

Sadly, parsed_args.my_bool evaluates to True. This is the case even when I change cmd_line to be ["--my_bool", ""], which is surprising, since bool("") evalutates to False.

How can I get argparse to parse "False", "F", and their lower-case variants to be False?

Solution

  • Simplest & most correct way is:

    from distutils.util import strtobool

parser.add_argument('--feature', dest='feature', 
                    type=lambda x: bool(strtobool(x)))

    Do note that True values are y, yes, t, true, on and 1; false values are n, no, f, false, off and 0. Raises ValueError if val is anything else.