Data Structures in Python: Lists, Tuples, and Dictionaries

Data Structures in Python: Lists, Tuples, and Dictionaries (Beginner’s Guide)

Introduction

In Python, data structures are used to store and organize data efficiently.
The three most commonly used are:

1. List → Ordered, changeable collection

2. Tuple → Ordered, unchangeable collection

3. Dictionary → Key-value pairs

Mastering these is essential for solving real-world problems and preparing for coding interviews.

1. Python Lists

• A list is an ordered collection that is mutable (can be changed).

• Defined using square brackets [].

Example:

fruits = ["apple", "banana", "cherry"]
print(fruits[0])     # Output: apple

fruits.append("mango")
print(fruits)        # Output: ['apple', 'banana', 'cherry', 'mango']

* Use a list when you need a dynamic collection that can change over time.

 2. Python Tuples

• A tuple is similar to a list but immutable (cannot be changed).

• Defined using parentheses ().

Example:

colors = ("red", "green", "blue")
print(colors[1])    # Output: green

# Trying to modify tuple → Error
# colors[0] = "yellow"  #Invalid

<> Use a tuple when you need a fixed collection that should not change.

3. Python Dictionaries

• A dictionary stores data as key-value pairs.

• Defined using curly braces {}.

Example:

student = {
    "name": "Arjun",
    "age": 21,
    "course": "Computer Science"
}

print(student["name"])   # Output: Arjun
student["age"] = 22      # Update value
print(student)

=>Use a dictionary when you want to map keys to values (like storing student details).

4. Differences Between List, Tuple, and Dictionary

5. Real-World Examples

• List → Shopping cart items in an e-commerce site

• Tuple → Latitude & Longitude coordinates (fixed values)

• Dictionary → Storing user profiles (name, email, password)

Challenge for You

Write a Python program that stores 5 student records using a dictionary.
Each student should have: name, roll_no, and marks.
Print details of the student with the highest marks., 

Summary

• Use Lists when data changes frequently.

• Use Tuples when data is constant.

• Use Dictionaries for mapping key-value pairs.

Understanding these three data structures will make your Python coding much easier and efficient.