---

Python Data Structures — Lists, Tuples, and Dictionaries

Python Data Structures help you store and organize data efficiently. The three most commonly used data structures are Lists, Tuples, and Dictionaries. Below is a clear overview with examples and mini challenges to practice your skills.

---

What Are Data Structures?

A data structure is a way of organizing and storing data so it can be used efficiently. Python has several built-in data structures, but the most common ones are:

• Lists — Ordered and mutable collections
• Tuples — Ordered but immutable collections
• Dictionaries — Key-value pairs, unordered and mutable

---

1. Python Data Structures: Lists — The All-Rounder

A list is an ordered, mutable collection that can hold numbers, strings, or even other lists.

Creating a List

fruits = ["apple", "banana", "mango", "orange"]
numbers = [1, 2, 3, 4, 5]
mixed = [1, "hello", 3.5, True]

Accessing Elements

print(fruits[0])  # apple
print(fruits[2])  # mango

Modifying Lists

fruits[1] = "grape"

Adding Items

fruits.append("cherry")        # Add at the end
fruits.insert(1, "kiwi")       # Add at specific index
fruits.extend(["pineapple", "pear"])  # Add multiple items

Removing Items

fruits.remove("apple")  # Remove by value
fruits.pop(0)           # Remove by index
fruits.clear()          # Remove all items

Looping Through a List

for fruit in fruits:
    print(fruit)

Useful Functions

• len(list) → Count items
• sum(list) → Sum of numbers
• sorted(list) → Sort items

Mini Challenge

Write a program that takes 5 numbers from the user and prints:

• Largest number
• Smallest number
• Sum of all numbers

---

2. Python Data Structures: Tuples — The Unchangeable List

A tuple is ordered like a list but immutable — its contents cannot be changed.

Creating a Tuple

colors = ("red", "green", "blue")

Accessing Elements

print(colors[0])  # red
print(colors[2])  # blue

You Cannot Modify a Tuple

# colors[1] = "yellow"  # ❌ Error

Looping Through a Tuple

for color in colors:
    print(color)

Tuple Operations

• Concatenation: (1,2) + (3,4) → (1,2,3,4)
• Repetition: ("Hi",) * 3 → ('Hi', 'Hi', 'Hi')
• Length: len(colors) → 3

Mini Challenge

Create a tuple with your 3 favorite movies and print them one by one.

---

3. Python Data Structures: Dictionaries — Key-Value Powerhouse

A dictionary stores data in key-value pairs. It is unordered and mutable.

Creating a Dictionary

student = {
    "name": "Alice",
    "age": 20,
    "course": "Python"
}

Accessing Values

print(student["name"])       # Alice
print(student.get("course")) # Python

Adding or Updating Items

student["age"] = 21           # Update
student["city"] = "New York"  # Add

Removing Items

student.pop("course")       # Remove by key
del student["city"]         # Remove key
student.clear()             # Remove all items

Looping Through a Dictionary

for key, value in student.items():
    print(key, ":", value)

Useful Methods

• keys() → List all keys
• values() → List all values
• items() → List all key-value pairs
• update() → Add multiple items

Mini Challenge

Create a dictionary for a book with keys: Title, Author, Price. Print all details neatly.

---

Combining Data Structures

You can nest lists, tuples, and dictionaries for advanced data storage.

Example: List of Dictionaries

students = [
    {"name": "Alice", "marks": 85},
    {"name": "Bob", "marks": 78},
    {"name": "Charlie", "marks": 92}
]

for s in students:
    print(s["name"], "scored", s["marks"])

Output:

Alice scored 85
Bob scored 78
Charlie scored 92

---

Practice Tasks

1. Create a list of 5 fruits and remove the 3rd one.
2. Store a tuple of 3 countries and print them using a loop.
3. Create a dictionary of 3 students (name: marks) and print each name with marks.
4. Write a program that takes a list of numbers and prints only the even ones.
5. Bonus: Make a mini phonebook using a dictionary (name as key, number as value).
6. Extra Practice: Combine a list, tuple, and dictionary in a single program to store and display different types of data.

---

Python Data Structures help you store and organize data efficiently. The three most commonly used data structures are Lists, Tuples, and Dictionaries. Below is a clear overview with examples and mini challenges to practice your skills.

Summary of Key Skills

• Use Lists, Tuples, and Dictionaries
• Add, remove, and access items
• Loop through data structures
• Combine them for complex storage

These are fundamental skills for Python programmers, enabling you to build apps like contact books, student databases, and small games.

---