How to Program to Flatten a Nested List in Python

Submitted by razormist on Thursday, April 10, 2025 - 23:20.

In this tutorial, we’ll learn how to program "How to Flatten a Nested List in Python". The objective is to safely flatten any nested list into a single-level list. This tutorial will guide you through the process step by step, helping you understand how to handle nested structures and convert them into a flat format. By the end, you’ll have a clear understanding of how to efficiently perform this task in Python.

This topic is straightforward to understand. Just follow the instructions I provide, and you’ll complete it with ease. The program I’ll demonstrate will show you the correct and efficient way to flatten a nested list into a single-level list. So, let’s dive into the coding process!

Getting Started:

First you will have to download & install the Python IDLE's, here's the link for the Integrated Development And Learning Environment for Python https://www.python.org/downloads/.

Creating Main Function

This is the main function of the application. The following code will display a simple GUI in terminal console that will display program. To do this, simply copy and paste these blocks of code into the IDLE text editor.

while True:
    print("\n============= Program to Flatten a Nested List =============\n")
 
 
    my_list = [[1], [2, 3], [4, 5, 6, 7], [8,9]]
 
    flat_list = []
    for sublist in my_list:
        for num in sublist:
            flat_list.append(num)
 
    print(flat_list)
 
    opt = input("\nDo you want to try again?(yes/no): ")
       
    if opt.lower() == 'yes':
        ret=False
    elif opt.lower() == 'no':
        ret=True
        print("Exiting program....")
    else:
        print("Please enter yes/no:")
        break
 
    if ret == False:
        continue

This program continuously flattens a nested list by going through each sublist and collecting all the individual elements into a single list, displaying the result each time until the user chooses to exit.

Output:

There you have it we successfully created How to Program to Flatten a Nested List in Python. I hope that this simple tutorial help you to what you are looking for. For more updates and tutorials just kindly visit this site. Enjoy Coding!

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