Lists: Your First Data Structure

Learning Objectives: After this lesson, you'll master Python lists for storing collections of data, understand indexing and slicing, and learn essential list methods for data manipulation.

What are Lists?

A list is Python's most versatile data structure - an ordered collection that can store multiple items of any type. Think of it as a container with numbered slots, where each slot can hold any Python value.

List Indexing

Each item in a list has an index (position number). Python uses zero-based indexing:

List Slicing

Slicing lets you extract portions of a list using the syntax list[start:end:step]:

Essential List Methods

Lists come with many built-in methods for manipulation:

List Operations and Functions

Interactive List Visualization

Let's see how list operations work visually:

List Comprehensions (Preview)

A powerful Python feature for creating lists:

Working with Lists of Different Types

Common List Patterns

Practical Examples

Example 1: Grade Tracker

Example 2: Shopping Cart

Practice Exercises

Exercise 1: List Manipulation

Exercise 2: Word List Processor

Key Takeaways

✅ Lists are ordered collections - Items have specific positions (indices)
✅ Zero-based indexing - First item is at index 0, last at index -1
✅ Slicing syntax - list[start:end:step] extracts portions
✅ Mutable - Lists can be modified after creation
✅ Essential methods - append(), insert(), remove(), pop(), sort()
✅ List comprehensions - Concise way to create and filter lists
✅ Versatile - Can store any type of data, including other lists

Next Steps

In the next lesson, we'll explore dictionaries and sets - data structures that excel at storing key-value pairs and unique collections respectively.

Ready to learn about Python's most powerful data structures? The next lesson will introduce dictionaries and sets!