CODEWITHSUNDEEP
pythonargparse
Andy
Andy

Reputation: 415

Infinite Amount of Command Line Arguments in Python

I am trying to create a simple calculator where it accepts arguments at the command line. For example at the command line: 

Calculator.py 1 2 44 6 -add

will give me the sum of the numbers. However, how can the user input infinite amount of arguments. I know you have to use *args or something of the like in functions and i just wanted to know how to incorporate that in the command line using argparse.

Upvotes: 1

Views: 4024

Answers (3)

Deborah Afolayan
Deborah Afolayan

Reputation: 1

import argparse

def operate_numbers(numbers, operation):
    return operation(*numbers)

def main():
    parser = argparse.ArgumentParser(description="Simple calculator script")
    parser.add_argument('numbers', type=int, nargs='+', help='Numbers to operate on')
    parser.add_argument('-operation', choices=['add', 'subtract', 'multiply', 'divide'], required=True, help='Operation to perform')

    args = parser.parse_args()

    operations = {
        'add': sum,
        'subtract': lambda x: x[0] - sum(x[1:]),
        'multiply': lambda x: eval('*'.join(map(str, x))),
        'divide': lambda x: eval('/'.join(map(str, x)))
    }

    result = operate_numbers(args.numbers, operations[args.operation])
    print("Result:", result)

if __name__ == "__main__":
    main()

Upvotes: 0

Jiminion
Jiminion

Reputation: 5178

import argparse

parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('integers', metavar='N', type=int, nargs='+',
               help='an integer for the accumulator')
parser.add_argument('--sum', dest='accumulate', action='store_const',
               const=sum, default=max,
               help='sum the integers (default: find the max)')

args = parser.parse_args()
print args.accumulate(args.integers)

https://docs.python.org/3/library/argparse.html

Upvotes: 5

Sukrit Kalra
Sukrit Kalra

Reputation: 34513

You don't need to, command line arguments are stored in sys.argv which will give you a list of the command line arguments. You just need to sum over them.

from sys import argv

print sum(map(int, argv[1:]))  # We take a slice from 1: because the 0th argument is the script name.

And just do

python testScript.py 1 2 3
6

P.S - Command line arguments are stored as strings, so you need to map them to integers to sum over them.

*args is used when you need to pass unknown number of values to a function. Consider the following - 

>>> def testFunc(*args):
        return sum(args)

>>> testFunc(1, 2, 3, 4, 5, 6)
21

Upvotes: 8

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