Template script reading from input file

script_with_input.py

"""
Template script with input file.

Use the module docstring as the script description.

Example usage: script.py -a 100 < infile

"""
import sys
from argparse import ArgumentParser, FileType


def parse_args():
    """Command line parser."""
    parser = ArgumentParser(description=__doc__)
    parser.add_argument('-i', '--infile', nargs='?', type=FileType('r'),
                        default=sys.stdin)
    parser.add_argument('-o', '--outfile', nargs='?', type=FileType('w'),
                        default=sys.stdout)
    parser.add_argument('-a',
                        '--arg',
                        type=float,
                        help='Example argument',
                        default=None)
    return parser.parse_args()


def main():
    """Main script."""

    args = vars(parse_args())  # parsed args as a dict
    infile = args.pop('infile')
    outfile = args.pop('outfile')

    print(
        'Input file: %r\n'
        'Output file: %r\n'
        'Arguments: %r' % (infile, outfile, args)
    )


if __name__ == '__main__':
    main()