Python argparse with choices

Question

I want to run my python program from the command line with some options. E.g. say my program has 4 modes, and I want it to use mode 2 by giving it the following arguments:

$ python main.py --mode 2

(And similarly for modes 1, 3, 4). How can I achieve this using argparse?

Ragnar Kruse · Accepted Answer · 2020-07-15 11:44:42Z

10

import argparse


parser = argparse.ArgumentParser(description='PROJECT_NAME')
parser.add_argument(
    '--mode', '-m',
    help='Set mode',
    default=1,
    type=int,
    choices=[1,2,3,4],
)
args = parser.parse_args()

print(args.mode)

For a complete list of the options available visit the docs:

https://docs.python.org/3/library/argparse.html

Update:

Added the suggestions from MaLiN2223's comment

edited Jul 15, 2020 at 11:44

answered Jul 5, 2020 at 21:51

Ragnar Kruse

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4 Comments

mss Over a year ago

Thank you! What is the '-m' part doing here?

MaLiN2223 Over a year ago

I would also add type=int in the name of 'fail early' principle (and so you don't have to do it yourself). Maybe also choices=[1,2,3,4] ?

Ragnar Kruse Over a year ago

just a optional shorthand so you can write python main.py -m 2

SethMMorton Over a year ago

This answer doesn't actually answer the question of how to limit to four choices. To be complete, this needs to include the comment from @MaLiN2223.

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