beginner⏱30 minutesLesson 7 of 10

Lists and Tuples

Learn Python's sequence types: list operations, tuple immutability, indexing, slicing, and common methods

Lists and Tuples

Lists and tuples are Python's workhorse data structures for storing ordered collections of items.

Lists (list)

Lists are mutable (can be changed) ordered sequences:

python
# Creating lists fruits = ["apple", "banana", "cherry"] mixed = [1, "hello", 3.14, True] empty = [] nested = [[1, 2], [3, 4]]

Indexing

python
fruits = ["apple", "banana", "cherry", "date"] print(fruits[0]) # "apple" (first) print(fruits[-1]) # "date" (last) print(fruits[1:3]) # ["banana", "cherry"] (slicing)

Modifying Lists

python
fruits[1] = "blueberry" # Change element fruits.append("elderberry") # Add to end fruits.insert(0, "avocado") # Insert at position fruits.remove("cherry") # Remove by value popped = fruits.pop() # Remove and return last del fruits[0] # Delete by index

List Methods

python
numbers = [3, 1, 4, 1, 5, 9, 2] numbers.sort() # [1, 1, 2, 3, 4, 5, 9] numbers.reverse() # [9, 5, 4, 3, 2, 1, 1] print(len(numbers)) # 7 print(numbers.count(1)) # 2 print(3 in numbers) # True

List Operations

python
# Concatenation a = [1, 2] + [3, 4] # [1, 2, 3, 4] # Repetition b = ["ha"] * 3 # ["ha", "ha", "ha"] # List comprehension (advanced preview) squares = [x**2 for x in range(5)] # [0, 1, 4, 9, 16]

Tuples (tuple)

Tuples are immutable (cannot change) ordered sequences:

python
# Creating tuples point = (3, 4) colors = ("red", "green", "blue") single = (1,) # Trailing comma required! empty = () # Empty tuple

Accessing Tuple Elements

python
point = (3, 4) x = point[0] # 3 y = point[1] # 4

Tuple Unpacking

python
point = (3, 4) x, y = point # x=3, y=4 # Swap variables elegantly a, b = 1, 2 a, b = b, a # a=2, b=1
ℹ️Note

Tuples are faster than lists and protect data integrity. Use them for fixed data like coordinates, RGB colors, or function return values.

When to Use Which

FeatureListTuple
Mutable?YesNo
Syntax[1, 2, 3](1, 2, 3)
PerformanceSlowerFaster
Use caseChanging dataFixed data
MethodsMany (append, sort, etc.)Few (count, index)

Real-World Examples

Shopping Cart (List — changes often)

python
cart = [] cart.append("laptop") cart.append("mouse") cart.append("keyboard") total_items = len(cart) print(f"Cart has {total_items} items")

RGB Color (Tuple — fixed)

python
RED = (255, 0, 0) GREEN = (0, 255, 0) BLUE = (0, 0, 255) def apply_color(pixel, color): r, g, b = color return (pixel[0] * r // 255, pixel[1] * g // 255, pixel[2] * b // 255)

Student Grades

python
grades = [85, 92, 78, 90, 88] average = sum(grades) / len(grades) print(f"Average: {average:.1f}") max_grade = max(grades) min_grade = min(grades) print(f"Range: {min_grade} - {max_grade}")
✅Success

Lists are for collections that change. Tuples are for collections that don't. When in doubt, use lists.

Practice Questions

  1. Create a list of 5 favorite foods. Print the third item.
  2. What's the difference between list.append() and list.insert()?
  3. How do you get the last element of a list?
  4. Why would you use a tuple instead of a list?
  5. What does [1, 2, 3] * 3 produce?
  6. How do you create a tuple with one element?
  7. Write code that swaps a = 5 and b = 10 using tuple unpacking.
  8. What's the output of [x*2 for x in range(4)]?
  9. How do you check if an item exists in a list?
  10. What happens if you try my_tuple[0] = 5?
Progress70%
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Course Content

1. What is Python?2. Installation and Setup3. Variables and Data Types4. Operators and Expressions5. Conditionals (if/elif/else)6. Loops (for and while)7. Lists and Tuples8. Dictionaries and Sets9. Functions and Scope10. Modules, Packages, and Standard Library