Python Concepts for Data Science: *args and *kwargs

Introduction to *args and **kwargs 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 (Non Keyword Arguments)

2. **kwargs (Keyword Arguments)

In this post i will explain the python concept *args and **kwargs with the calculation of area of rectangle.

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

Python *args

Python *args allow us to pass the variable number of non keyword arguments to function.

In the function, we should use an asterisk * before the parameter name to pass variable length arguments.The arguments are passed as a tuple and these passed arguments make tuple inside the function with same name as the parameter excluding asterisk *.

Python **kwargs

Python passes variable length non keyword argument to function using *args but we cannot use this to pass keyword argument. For this problem Python has got a solution called **kwargs, it allows us to pass the variable length of keyword arguments to the function.

In the function, we use the double asterisk ** before the parameter name to denote this type of argument. The arguments are passed as a dictionary and these arguments make a dictionary inside function with name same as the parameter excluding double asterisk.

Let's explain *arg and **kwargs with this example below

def area_rectangle(*args):  
    if len(args) == 2:
        return args[0]*args[1]
    else:
        print('Please state two parameters')

#Python *kwargs

def area_rectangle2(**kwargs):  
    if len(kwargs) == 2:
        result = 1
        for key, value in kwargs.items():
            result *=value
        return result
    else:
        print('Please state two parameters')

if __name__ == '__main__':
    print (area_rectangle(3,8))
    print (area_rectangle2(cote1=4, cote2=8))

Here is the result of this code

Thank you for reading!

You can find the complete source code here Github