Python Lists: Basics, Operations, and Examples

Learn the fundamentals of Python lists, including creation, manipulation, indexing, and common operations. Explore practical examples and best practices.

Table of Contents

1. Introduction to Lists
2. Characteristics of Lists
3. Creating a List
4. Accessing Elements
5. Modifying Elements
6. Iterating Through a List
7. Practice Tasks

Introduction

• A list in Python is one of the most commonly used data structures. It allows you to store a collection of items (which can be of different types) in a single variable. Lists are very flexible and easy to use, making them a great tool for beginners to understand.

Key Characteristics of Lists:

1. Ordered: The items in a list have a specific order, and this order will not change unless explicitly modified.
2. Mutable: You can change, add, or remove items after the list has been created.
3. Heterogeneous: A list can contain different data types, such as integers, strings, and even other lists.
4. Indexed: Each item in a list has an index, starting from 0 for the first item.

Creating a List

You can create a list by placing items inside square brackets [], separated by commas.

# A list of integers
numbers = [1, 2, 3, 4, 5]

# A list of strings
fruits = ["apple", "banana", "cherry"]

# A list of mixed data types
mixed_list = [1, "hello", 3.14, True]

# An empty list
empty_list = []

Accessing Elements in a List using Index

You can access individual elements in a list using their index.

# Access the first element (index 0)
print(fruits[0])  # Output: apple

# Access the second element (index 1)
print(fruits[1])  # Output: banana

# Access the last element (index -1)
print(fruits[-1])  # Output: cherry

Modifying Elements in a List using Index

Since lists are mutable, you can change an element in a list by assigning a new value to a specific index.

# Change the first element of the list
fruits[0] = "orange"
print(fruits)  # Output: ['orange', 'banana', 'cherry']

List Operations

# Concatenation
new_list = [1, 2] + [3, 4]  # [1, 2, 3, 4]

# Repetition
repeated = [0] * 3          # [0, 0, 0]

# Membership testing
if 'a' in my_list:
    print("Found!")

# Length
length = len(my_list)       # Number of elements

Iterating Through a List

You can use a loop to iterate through all the elements in a list.

# Print each fruit in the list
for fruit in fruits:
    print(fruit)

# Output:
# mango
# grape

📺 Video Tutorial: Lists in Python

This video covers:

• ✔️ How to create lists.
• ✔️ Accessing List Elements
  • Positive indexing (list[0] for the first item)
  • Negative indexing (list[-1] for the last item)
• ✔️ length of the list.

📺 Video Tutorial: 6 Ways to use List in For loop in Python

This video covers:

• ✔️ The basic method for printing the values of a list [00:08].
• ✔️ Accessing the index and values of a list [00:50].
• ✔️ Modifying elements within a list [01:29].
• ✔️ Creating a new list using list comprehension [02:28].
• ✔️ Filtering items in a list based on a condition [03:09].
• ✔️ Using nested for loops with lists [03:56].

✅ Tasks

Task 1: Creating a List

Write a Python program that:

• Creates a list of four favorite foods.
• Prints the entire list.
• Prints the second food from the list.

Example Output:

Favorite Foods: ['Pizza', 'Burger', 'Pasta', 'Ice Cream']
Second food: Burger

Task 2: Changing an Item in a List

Write a Python program that:

• Creates a list with three colors.
• Changes the first color to a new one.
• Prints the updated list.

Example Output:

Original List: ['Red', 'Blue', 'Green']
Updated List: ['Yellow', 'Blue', 'Green']

Task 3: Creating and Accessing a List

Write a Python program that:

• Creates a list of five Islamic boys’ names.
• Prints the entire list.
• Accesses and prints the third name in the list using indexing.
• Changes the last name in the list to a new name.
• Prints the updated list.

Example Output:

Original List: ['Ahmed', 'Hassan', 'Omar', 'Yusuf', 'Zayd']
Third name: Omar
Updated List: ['Ahmed', 'Hassan', 'Omar', 'Yusuf', 'Bilal']

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