Cannot parse boolean values with argparse

Question

Things I have tried but did not work:

parser.add_argument('--download',type=bool,default=False)
parser.add_argument('--download',default=False,action='store_true')
parser.add_argument('--download',action='store_true')

For case 1, Passing False also gets interpreted as True. For case 2 and 3, I get the error

main.py: error: unrecognized arguments: False

Python version : 3.8

Why does argparse not work for boolean arguments?

The use of bool at the type function is mentioned in the docs: docs.python.org/3/library/argparse.html#type — hpaulj
– hpaulj, Commented Feb 26, 2022 at 8:53

khelwood · Accepted Answer · 2022-02-26 07:22:24Z

1

The way 'store_true' works is that if you give --download as an argument, then the value is true; and if you omit it, it is false.

The reason type=bool doesn't work as you want is that any nonempty string passed to the bool function will result in True. (You could, if you wanted, write a function that returns True if the string is "True" and False if it is "False", and use that for type, but that is not the typical use-case.)

edited Feb 26, 2022 at 7:22

answered Feb 26, 2022 at 7:20

khelwood

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