Topic 8118 min readStructured Tutorial

Python Arbitrary Arguments

Quick Answer

Arbitrary Arguments explains in Python, functions can accept a variable number of arguments using arbitrary arguments.

Learning Objectives

Explain the purpose of Arbitrary Arguments in a practical learning context.
Identify the main ideas, terms, and decisions involved in Arbitrary Arguments.
Apply Arbitrary Arguments in a simple real-world scenario or practice task.

Introduction

In Python, functions can accept a variable number of arguments using arbitrary arguments.

This tutorial explains how to use *args and **kwargs to handle flexible function inputs.

Flexibility in function arguments leads to more reusable and adaptable code.

Understanding Arbitrary Positional Arguments (*args)

The *args syntax allows a function to accept any number of positional arguments as a tuple.

This is useful when you do not know in advance how many arguments will be passed.

*args collects extra positional arguments into a tuple.
You can iterate over *args inside the function.
*args must come after regular positional parameters.

Example of *args

Here is a simple function that sums any number of numeric arguments using *args.

Understanding Arbitrary Keyword Arguments (**kwargs)

**kwargs allows a function to accept any number of keyword arguments as a dictionary.

This is useful when you want to handle named arguments that you did not explicitly define.

**kwargs collects extra keyword arguments into a dictionary.
You can access keys and values inside the function.
**kwargs must come after *args if both are used.

Example of **kwargs

Here is a function that prints all keyword arguments passed to it.

Combining *args and **kwargs

You can define functions that accept both arbitrary positional and keyword arguments.

This makes your functions highly flexible and able to handle various input scenarios.

The order in the function definition should be: regular parameters, *args, then **kwargs.
Inside the function, *args is a tuple and **kwargs is a dictionary.

Example Combining *args and **kwargs

This example demonstrates a function that prints all positional and keyword arguments.

Practical Example

This function sums any number of numeric arguments passed to it using *args.

This function prints all keyword arguments passed to it using **kwargs.

This function accepts both arbitrary positional and keyword arguments and prints them.

Examples

Using *args to Sum Numbers

def sum_numbers(*args):
    total = 0
    for num in args:
        total += num
    return total

print(sum_numbers(1, 2, 3, 4))  # Output: 10

This function sums any number of numeric arguments passed to it using *args.

Using **kwargs to Print Keyword Arguments

def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

print_info(name='Alice', age=30)

This function prints all keyword arguments passed to it using **kwargs.

Combining *args and **kwargs

def show_args(*args, **kwargs):
    print('Positional arguments:', args)
    print('Keyword arguments:', kwargs)

show_args(1, 2, name='Bob', age=25)

This function accepts both arbitrary positional and keyword arguments and prints them.

Best Practices

Use *args and **kwargs to make functions flexible and reusable.
Name *args and **kwargs exactly as shown for readability and convention.
Avoid overusing arbitrary arguments to keep function interfaces clear.
Document what kinds of arguments your function expects even if using *args or **kwargs.

Common Mistakes

Placing *args after **kwargs in function definitions (order matters).
Using *args or **kwargs without unpacking when calling other functions.
Assuming *args is a list instead of a tuple.
Modifying the *args tuple inside the function (tuples are immutable).

Hands-on Exercise

Create a Function Using *args

Write a function that takes any number of numeric arguments and returns their average using *args.

Expected output: The average of the numbers passed.

Hint: Sum all numbers in *args and divide by the length of *args.

Create a Function Using **kwargs

Write a function that accepts any keyword arguments and prints them in the format 'key = value'.

Expected output: Printed key-value pairs for all keyword arguments.

Hint: Iterate over kwargs.items() and print each pair.

Interview Questions

What are *args and **kwargs in Python?

Interview

*args allows a function to accept any number of positional arguments as a tuple, while **kwargs allows a function to accept any number of keyword arguments as a dictionary.

Can you use *args and **kwargs together in a function?

Interview

Yes, you can define a function with both *args and **kwargs to accept arbitrary positional and keyword arguments. The order must be: regular parameters, *args, then **kwargs.

What is Arbitrary Arguments, and why is it useful?

Beginner

In Python, functions can accept a variable number of arguments using arbitrary arguments.