python argparse get argument value code example

Example 1: python argparse

import argparse

# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-n", "--name", required=True, help="name of the user")
args = vars(ap.parse_args())

# display a friendly message to the user
print("Hi there {}, it's nice to meet you!".format(args["name"]))

Example 2: 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 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: 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 5: 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":
    ...

Example 6: argparse python

# Generic parser function intialization in PYTHON
def create_parser(arguments):
    """Returns an instance of argparse.ArgumentParser"""
    # your code here
    
    parser = argparse.ArgumentParser(
        description="Description of your code")
    parser.add_argument("argument", help="mandatory or positional argument")
    parser.add_argument("-o", "--optional", 
    	help="Will take an optional argument after the flag")
    namespace = parser.parse_args(arguments)
    
    # Returns a namespace object with your arguments
    return namespace