7. Lists, Tuples, and Sets

What Are Collections in Python?

So far, we've worked with single values like strings and numbers. But what if you want to store multiple values together—like a list of students or favorite colors? That's where Python collection types come in.

In this lesson, we’ll cover three important built-in collections:

• Lists – ordered and changeable
• Tuples – ordered but not changeable
• Sets – unordered and unique values

Lists

A list is used to store multiple items in a single variable. Lists are changeable, meaning you can add, remove, or modify elements.

fruits = ["apple", "banana", "cherry"]
print(fruits)  # ['apple', 'banana', 'cherry']

List Operations

# Access items
print(fruits[0])  # apple

# Modify items
fruits[1] = "orange"

# Add items
fruits.append("mango")
fruits.insert(1, "blueberry")

# Remove items
del fruits[2]
fruits.remove("mango")

Tuples

Tuples are like lists, but **they cannot be changed** after creation. Use tuples when you want a collection of data that should not be modified.

colors = ("red", "green", "blue")
print(colors[0])  # red

Tuples are faster and more memory-efficient than lists, which makes them perfect for **fixed data**.

Sets

A set is a collection that stores **unique values** and does **not keep order**.

numbers = {1, 2, 3, 3, 4}
print(numbers)  # {1, 2, 3, 4}

Sets are great for removing duplicates or performing mathematical set operations like union and intersection.

evens = {2, 4, 6}
odds = {1, 3, 5}
primes = {2, 3, 5}

print(evens.union(odds))        # {1, 2, 3, 4, 5, 6}
print(evens.intersection(primes))  # {2}

When Should You Use Each?

Mini Exercise

Create a list of three favorite foods. Update the second item, add a new item, and remove one item.

# Your turn!
favorite_foods = ["rice", "pizza", "pasta"]
# 1. Change one item
# 2. Add a new item
# 3. Remove one item
print(favorite_foods)