Parsing boolean values with argparse

do · EDIT:

my_program --my_boolean_flag False

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)

from distutils.util import strtobool

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

command --feature

command --no-feature

parser.add_argument('--feature', action=argparse.BooleanOptionalAction)

parser.add_argument('--feature', action='store_true')
parser.add_argument('--no-feature', dest='feature', action='store_false')
parser.set_defaults(feature=True)

def t_or_f(arg):
    ua = str(arg).upper()
    if 'TRUE'.startswith(ua):
       return True
    elif 'FALSE'.startswith(ua):
       return False
    else:
       pass  #error condition maybe?

def str2bool(v):
    if isinstance(v, bool):
        return v
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        raise argparse.ArgumentTypeError('Boolean value expected.')

parser.add_argument("--nice", type=str2bool, nargs='?',
                        const=True, default=False,
                        help="Activate nice mode.")

script --nice
script --nice <bool>

parser.add_argument('--feature', default=True, action=argparse.BooleanOptionalAction)

parser.add_argument('--feature', dest='feature', action='store_true')
parser.add_argument('--no-feature', dest='feature', action='store_false')
parser.set_defaults(feature=True)

feature_parser = parser.add_mutually_exclusive_group(required=False)
feature_parser.add_argument('--feature', dest='feature', action='store_true')
feature_parser.add_argument('--no-feature', dest='feature', action='store_false')
parser.set_defaults(feature=True)

def add_bool_arg(parser, name, default=False):
    group = parser.add_mutually_exclusive_group(required=False)
    group.add_argument('--' + name, dest=name, action='store_true')
    group.add_argument('--no-' + name, dest=name, action='store_false')
    parser.set_defaults(**{name:default})

add_bool_arg(parser, 'useful-feature')
add_bool_arg(parser, 'even-more-useful-feature')

import argparse
parser = argparse.ArgumentParser(description="Parse bool")
parser.add_argument("--do-something", default=False, action="store_true",
                    help="Flag to do something")
args = parser.parse_args()

if args.do_something:
     print("Do something")
else:
     print("Don't do something")

print(f"Check that args.do_something={args.do_something} is always a bool.")

parser.add_argument('--is_debug', default=False, type=lambda x: (str(x).lower() == 'true'))

parser._registries

{'action': {None: argparse._StoreAction,
  'append': argparse._AppendAction,
  'append_const': argparse._AppendConstAction,
...
 'type': {None: <function argparse.identity>}}

def str2bool(v):
  #susendberg's function
  return v.lower() in ("yes", "true", "t", "1")
p = argparse.ArgumentParser()
p.register('type','bool',str2bool) # add type keyword to registries
p.add_argument('-b',type='bool')  # do not use 'type=bool'
# p.add_argument('-b',type=str2bool) # works just as well
p.parse_args('-b false'.split())
Namespace(b=False)

from distutils.util import strtobool

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

feature.add_argument('--feature',action='store_true')

 command --feature

def str2bool(v):
  return v.lower() in ("yes", "true", "t", "1")

add_boolean_argument(parser, 'foo', default=True)
parser.parse_args([])                   # Whatever the default was
parser.parse_args(['--foo'])            # True
parser.parse_args(['--nofoo'])          # False
parser.parse_args(['--foo=true'])       # True
parser.parse_args(['--foo=false'])      # False
parser.parse_args(['--foo', '--nofoo']) # Error

def _str_to_bool(s):
    """Convert string to bool (in argparse context)."""
    if s.lower() not in ['true', 'false']:
        raise ValueError('Need bool; got %r' % s)
    return {'true': True, 'false': False}[s.lower()]

def add_boolean_argument(parser, name, default=False):                                                                                               
    """Add a boolean argument to an ArgumentParser instance."""
    group = parser.add_mutually_exclusive_group()
    group.add_argument(
        '--' + name, nargs='?', default=default, const=True, type=_str_to_bool)
    group.add_argument('--no' + name, dest=name, action='store_false')

  parser.add_argument('--boolean_flag',
                      help='This is a boolean flag.',
                      type=eval, 
                      choices=[True, False], 
                      default='True')

import argparse

ap = argparse.ArgumentParser()

# List of args
ap.add_argument('--foo', default=True, type=bool, help='Some helpful text that is not bar. Default = True')

# Importable object
args = ap.parse_args()

parser.add_argument('--feature', type=lambda s: s.lower() in ['true', 't', 'yes', '1'])

import argparse
from distutils import util
parser.add_argument('--feature', type=util.strtobool)

>>> 0 == False
True
>>> 0 == True
False
>>> 1 == False
False
>>> 1 == True
True

python yours.py --feature wrong_value

yours.py: error: argument --feature: invalid strtobool value: 'wrong_value'

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

yours.py: error: argument --feature: invalid <lambda> value: 'wrong_value'

parser = argparse.ArgumentParser()
parser.add_argument('--my-flag',choices=('True','False'))

args = parser.parse_args()
flag = args.my_flag == 'True'
print(flag)

import argparse

parser = argparse.ArgumentParser(description="My parser")

parser.add_argument(
        "--my_bool",
        choices=["False", "True"],
        )

parsed_args = parser.parse_args()

my_bool = parsed_args.my_bool == "True"

print(my_bool)

$ python my_program.py --my_bool False
False

$ python my_program.py --my_bool True
True

$ python my_program.py --my_bool true
usage: my_program.py [-h] [--my_bool {False,True}]
my_program.py: error: argument --my_bool: invalid choice: 'true' (choose from 'False', 'True')

import argparse
from ast import parse
import sys
parser = argparse.ArgumentParser(description='')
parser.add_argument('--csv', action='store_true', default = False 
,help='read from csv')
args = parser.parse_args()

if args.csv:
    print('reading from csv')

parser.add_argument('--feature', default=False, type=lambda x: x == 'True')

import argparse
from distutils.util import strtobool

parser = argparse.ArgumentParser()
parser.add_argument("--foo", 
    type=lambda x:bool(strtobool(x)),
    nargs='?', const=True, default=False)
args = parser.parse_args()
print(args.foo)

(base) [costa@costa-pc code]$ python test.py
False
(base) [costa@costa-pc code]$ python test.py --foo 
True
(base) [costa@costa-pc code]$ python test.py --foo True
True
(base) [costa@costa-pc code]$ python test.py --foo False
False

parser.add_argument('--ensure', nargs='*', default=None)

ENSURE = config.ensure is None

parser.add_argument("mybool", default=True,type=lambda x: bool(int(x)))
myargs=parser.parse_args()
print(myargs.mybool)

python myscript.py 0

class FlagAction(argparse.Action):
    # From http://bugs.python.org/issue8538

    def __init__(self, option_strings, dest, default=None,
                 required=False, help=None, metavar=None,
                 positive_prefixes=['--'], negative_prefixes=['--no-']):
        self.positive_strings = set()
        self.negative_strings = set()
        for string in option_strings:
            assert re.match(r'--[A-z]+', string)
            suffix = string[2:]
            for positive_prefix in positive_prefixes:
                self.positive_strings.add(positive_prefix + suffix)
            for negative_prefix in negative_prefixes:
                self.negative_strings.add(negative_prefix + suffix)
        strings = list(self.positive_strings | self.negative_strings)
        super(FlagAction, self).__init__(option_strings=strings, dest=dest,
                                         nargs=0, const=None, default=default, type=bool, choices=None,
                                         required=required, help=help, metavar=metavar)

    def __call__(self, parser, namespace, values, option_string=None):
        if option_string in self.positive_strings:
            setattr(namespace, self.dest, True)
        else:
            setattr(namespace, self.dest, False)

import argparse
from distutils.util import strtobool

parser = argparse.ArgumentParser()
parser.add_argument("--my_bool", type=str, default="False")
args = parser.parse_args()

if bool(strtobool(args.my_bool)) is True:
    print("OK")

parser.add_argument("--test" , default=False ,help="test ?", dest='test', action='store_true')

def __arg_to_bool__(arg):
    """__arg_to_bool__

        Convert string / int arg to bool
    :param arg: argument to be converted
    :type arg: str or int
    :return: converted arg
    :rtype: bool
    """
    str_true_values = (
        '1',
        'ENABLED',
        'ON',
        'TRUE',
        'YES',
    )
    str_false_values = (
        '0',
        'DISABLED',
        'OFF',
        'FALSE',
        'NO',
    )

    if isinstance(arg, str):
        arg = arg.upper()
        if arg in str_true_values:
            return True
        elif arg in str_false_values:
            return False

    if isinstance(arg, int):
        if arg == 1:
            return True
        elif arg == 0:
            return False

    if isinstance(arg, bool):
        return arg

    # if any other value not covered above, consider argument as False
    # or you could just raise and error
    return False

[...]

args = ap.parse_args()
my_arg = options.my_arg
my_arg = __arg_to_bool__(my_arg)

class BoolAction(Action):
    def __init__(
            self,
            option_strings,
            dest,
            nargs=None,
            default: bool = False,
            **kwargs,
    ):
        if nargs is not None:
            raise ValueError('nargs not allowed')
        super().__init__(option_strings, dest, default=default, **kwargs)

    def __call__(self, parser, namespace, values, option_string=None):
        input_value = values.lower()
        b = input_value in ['true', 'yes', '1']
        if not b and input_value not in ['false', 'no', '0']:
            raise ValueError('Invalid boolean value "%s".)
        setattr(namespace, self.dest, b)

import argparse
if __name__=='__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--bool_flag', type=str)
    args = parser.parse_args()
    args.bool_flag = bool(eval(args.bool_flag))
    print(args.bool_flag, ',', type(args.bool_flag))

#!/bin/bash
flag=False
python tmp.py --bool_flag $flag

If you want to allow `--feature` and `--no-feature` at the same time (last one wins)

Python 3.9 and above

Python 3.8 and below

If you DON'T want to allow `--feature` and `--no-feature` at the same time

Recommended topics

Hot tags

If you want to allow --feature and --no-feature at the same time (last one wins)