Python 2.7 Argparse Yes or No input

You could simply add an argument with action='store_true', which will default args.calories to False if the --calories is not included. To further clarify, if the user adds --calories, args.calories will be set to True.

parser = argparse.ArgumentParser(description='Get food details.')# adding the `--food` argumentparser.add_argument('--food', help='name of food to lookup', required=True, type=file)# adding the `--calories` argumentparser.add_argument('--calories', action='store_true', dest='calories', help='...')# note: `dest` is where the result of the argument will go.# as in, if `dest=foo`, then `--calories` would set `args.foo = True`.# in this case, it's redundant, but it's worth mentioning.args = parser.parse_args()if args.calories:    # if the user specified `--calories`,     # call the `calories()` method    calories()else:    do_whatever()

If, however, you would like to specifically check for yes or no, then replace the store_true in

parser.add_argument('--calories', action='store_true', dest='calories', help='...')

with store, as shown below

parser.add_argument('--calories', action='store', dest='calories', type='str', help='...')

This will then allow you to check later for

if args.calories == 'yes':    calories()else:    do_whatever()

Do note that in this case I added type=str, which parses the argument as a string. Since you specified that the choices are either yes or no, argparse actually allows us to further specify the domain of possible inputs with choices:

parser.add_argument('--calories', action='store', dest='calories', type='str',                     choices=['yes', 'no'], help='...')

Now, if a user enters anything not in ['yes', 'no'], it will raise an error.

One last possibility is adding a default, such that users don't have to necessarily specify certain flags all the time:

parser.add_argument('--calories', action='store', dest='calories', type='str',                     choices=['yes', 'no'], default='no', help='...')

Edit: As @ShadowRanger pointed out in the comments, in this case, dest='calories', action='store', and type='str' are the defaults, so you can omit them:

parser.add_argument('--calories', choices=['yes', 'no'], default='no', help='...')