“*args” and “**kwargs” in Python

Knowing about the “*args” and “**kwargs” functional parameters in Python

In Python, we can pass a variable number of arguments to a function using special symbols. There are two special symbols:

1. *args stands for arguments.

2) **kwargs stands for keyword arguments.

We use *args and **kwargs as an argument when we are unsure about the number of arguments to pass in the functions.

>>> def func1(n1,n2):
        return sum((n1,n2))
>>> func1(2,4)
6

Now if I pass 3 arguments then we will have to change the function so it can take 3 arguments. Now instead of this, in cases where we are unaware of the number of arguments that will be passed, we can use args or kwargs.

args

It generates a tuple of values.

>>> def func1(*args):
        return sum(args)
>>> func1(1,2,3)
6

Notice when we print args, we get a tuple.

>>> def func1(*args):
        print(args)
        return sum(args)
>>> func1(3,4,5,6,7,8)
(3, 4, 5, 6, 7, 8)
33

Typically args is a tuple and it takes in any number and performs the function. args is just a keyword and can be changed, the * sign is important.

>>> def func1(*pizza):
        return sum(pizza)
>>> func1(1,2)
3
>>> def func2(*args):
        for i in args:
            print(i)
>>> func2(1,2,3,4,5)
1
2
3
4
5

kwargs

It generates a dictionary of key-value pairs.

>>> def func3(**kwargs):
        if 'coding' in kwargs:
         print("My favorite language is{}".format(kwargs['coding']))
        else:
         print("fail")
>>> func3(coding='python')
My favorite language is python

Now if we put more arguments while calling even though it is not mentioned in the function, it would not raise errors.

>>> func3(coding='python', editor='sublime')
My favorite language is python

Notice when we print kwargs, we get a dictionary.

>>> def func3(**kwargs):
       print(kwargs)
       if 'coding' in kwargs:
        print("My favorite language is {}".format(kwargs['coding']))
       else:
        print("fail")
>>> func3(coding='python', editor='sublime')
{'coding': 'python', 'editor': 'sublime'}
My favorite language is python

Again kwargs is just a keyword, the ** sign is important.

>>> def func3(**pizza):
       print(pizza)
       if 'coding' in pizza:
         print("My favorite language is {}".format(pizza['coding']))
       else:
         print("fail")
>>> func3(coding='python', editor='sublime')
{'coding': 'python', 'editor': 'sublime'}
My favorite language is python

Combination of args and kwargs

>>> def func4(*args, **kwargs):
     print(args)
     print(kwargs)
     print("I would love {} {}". format(args[0], kwargs['objects']))
>>> func4(4,2,3, objects="pencils", coding="python")
(4, 2, 3)
{'objects': 'pencils', 'coding': 'python'}
I would love 4 pencils

Refer to the notebook here.

Beginner-level books to refer to learn Python:

Python Crash Course, 2nd Edition: A Hands-On, Project-Based Introduction to Programming

Learn Python the Hard Way: A Very Simple Introduction to the Terrifyingly Beautiful World of…

Think Python, 2e: How to Think Like a Computer Scientist

Advance-level books to refer to learn Python:

Programming Python: Powerful Object-Oriented Programming

Advanced Python Programming: Build high performance, concurrent, and multi-threaded apps with…

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