Question

I would like to use argparse to take some (3) integer arguments, and use these as variables in the program body. Running the code below, each variable gets stored in a one element list. This is no big problem of course, but is it possible to set up the parser to put each value into a simple integer variable?

import argparse

def main():
    parser = argparse.ArgumentParser(description='three positional integer arguments.')
    parser.add_argument('picks', type=int, nargs='+', default=10,
                       help='number of selections per execution')
    parser.add_argument('minchunk', type=int, nargs='+', default=2,
                       help='min chunk size')
    parser.add_argument('maxchunk', type=int, nargs='+', default=8,
                       help='max chunk size')

    args = parser.parse_args(['1', '2', '3'])
    print args
    return 0

Answer 1

nargs = '+' tells argparse to collect 1 or more arguments in a list.
If you remove the nargs = '+':

import argparse

def main():
    parser = argparse.ArgumentParser(
        description = 'three positional integer arguments.')
    parser.add_argument('picks', type = int, default = 10, nargs = '?',
                       help = 'number of selections per execution')
    parser.add_argument('minchunk', type = int, default = 2, nargs = '?',
                       help = 'min chunk size')
    parser.add_argument('maxchunk', type = int, default = 8, nargs = '?',
                       help = 'max chunk size')

    args = parser.parse_args()
    print args

main()

yields

Namespace(maxchunk=3, minchunk=2, picks=1)