How to make an optional value for argument using argparse?
After a little more reading in the documentation I found what I needed: nargs='?'.This is used with the store action, and does exactly what I want.
Here is an example:
>>> import argparse>>> parser = argparse.ArgumentParser()>>> parser.add_argument('--head', dest='size', const=10, default=80, action='store', nargs='?', type=int, help='Only print the head of the output')>>> parser.parse_args(''.split())... Namespace(size=80)>>> parser.parse_args('--head'.split())... Namespace(size=10)>>> parser.parse_args('--head 15'.split())... Namespace(size=15)Source: http://docs.python.org/3/library/argparse.html#nargs