argparse example

Example 1: how to use argparse

import argparse

if __name__ == "__main__":
	#add a description
	parser = argparse.ArgumentParser(description="what the program does")

	#add the arguments
	parser.add_argument("arg1", help="advice on arg")
	parser.add_argument("arg2", help="advice on arg")
#						.
# 						.
#   					.
	parser.add_argument("argn", help="advice on arg")

	#this allows you to access the arguments via the object args
	args = parser.parse_args()

	#how to use the arguments
	args.arg1, args.arg2 ... args.argn

Example 2: argeparse can it take a type list

import argparse

parser = argparse.ArgumentParser()

# By default it will fail with multiple arguments.
parser.add_argument('--default')

# Telling the type to be a list will also fail for multiple arguments,
# but give incorrect results for a single argument.
parser.add_argument('--list-type', type=list)

# This will allow you to provide multiple arguments, but you will get
# a list of lists which is not desired.
parser.add_argument('--list-type-nargs', type=list, nargs='+')

# This is the correct way to handle accepting multiple arguments.
# '+' == 1 or more.
# '*' == 0 or more.
# '?' == 0 or 1.
# An int is an explicit number of arguments to accept.
parser.add_argument('--nargs', nargs='+')

# To make the input integers
parser.add_argument('--nargs-int-type', nargs='+', type=int)

# An alternate way to accept multiple inputs, but you must
# provide the flag once per input. Of course, you can use
# type=int here if you want.
parser.add_argument('--append-action', action='append')

# To show the results of the given option to screen.
for _, value in parser.parse_args()._get_kwargs():
    if value is not None:
        print(value)

Example 3: python argparse file argument

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('file', type=argparse.FileType('r'))
args = parser.parse_args()

print(args.file.readlines())

Example 4: python argument parser default value

parser.add_argument("-v", "--verbose", action="store_true",
                    default="your default value", help="verbose output")

Example 5: argparse accept only few options

...
parser.add_argument('--val',
                    choices=['a', 'b', 'c'],
                    help='Special testing value')

args = parser.parse_args(sys.argv[1:])

Example 6: use argparse to call function and use argument in function

# Parse the subcommand argument first
parser = ArgumentParser(add_help=False)
parser.add_argument("function", 
                    nargs="?",
                    choices=['function1', 'function2', 'function2'],
                    )
parser.add_argument('--help', action='store_true')
args, sub_args = parser.parse_known_args(['--help'])

# Manually handle help
if args.help:
    # If no subcommand was specified, give general help
    if args.function is None: 
        print parser.format_help()
        sys.exit(1)
    # Otherwise pass the help option on to the subcommand
    sub_args.append('--help')

# Manually handle the default for "function"
function = "function1" if args.function is None else args.function

# Parse the remaining args as per the selected subcommand
parser = ArgumentParser(prog="%s %s" % (os.path.basename(sys.argv[0]), function))
if function == "function1":
    parser.add_argument('-a','--a')
    parser.add_argument('-b','--b')
    parser.add_argument('-c','--c')
    args = parser.parse_args(sub_args)
    function1(args.a, args.b, args.c)
elif function == "function2":
    ...
elif function == "function3":
    ...