Module 2 Lesson 1: Introduction to Data Structures

In Module 1, we learned about basic variables like integers and strings. These are like single envelopes—one piece of data per name. But what if you wanted to store 100 players' scores, or a list of every country in the world? You wouldn't want to create 100 separate variables!

This is where Data Structures come in.

Lesson Overview

In this lesson, we will:

The Big Idea: Understanding data structures as "containers."
Efficiency: Why organization makes code faster.
The Python Four: A quick preview of Lists, Tuples, Dictionaries, and Sets.
Real-world Analogy: How we organize data in real life.

1. What is a Data Structure?

A data structure is a specialized way of organizing and storing data so that it can be accessed and worked with efficiently.

Think of your wardrobe.

If you throw all your clothes in one giant pile, it's a "structure," but it's hard to find your favorite blue shirt.
If you use hangers, drawers, and shelves, you have a solid data structure. You can find things quickly, add new things easily, and see what you're missing.

2. Why Do They Matter?

Data structures aren't just for organization; they are for Performance.

Speed: Some structures are faster at finding things (searching).
Memory: Some structures use less space than others.
Functionality: Some structures are built for specific tasks (like preventing duplicates).

3. The "Big Four" in Python

In this module, we will master the four primary built-in data structures in Python:

Lists: Ordered and changeable groups of items. (Your shopping list).
Tuples: Ordered but UNCHANGEABLE groups. (The coordinates of a city).
Dictionaries: Labeled pairs of data. (A phone book: Name -> Number).
Sets: Unordered groups with NO duplicates. (A collection of unique IDs).

4. How to Choose?

Choosing the right structure is half the battle in programming.

Need to keep things in order? Use a List.
Need to ensure no one changes the data? Use a Tuple.
Need to find value B by looking up key A? Use a Dictionary.
Need to filter out duplicates? Use a Set.

Practice Exercise: Data Brainstorming

Look at the following scenarios and decide (based on the definitions above) which Python data structure would be best:

A list of the high scores in a game (top 10).
Your birth date (Month, Day, Year) which will never change.
A collection of usernames where every name must be unique.
A grocery list where you might add or remove items.

Quick Knowledge Check

How is a data structure different from a simple variable?
Name one reason why using the right data structure is important.
True or False: A Python List can be changed after it is created.
Which data structure is best for storing "Key-Value" pairs?

Key Takeaways

Data structures are containers for multiple pieces of data.
Organization directly impacts how fast your program runs.
Python provides four powerful built-in structures: Lists, Tuples, Dictionaries, and Sets.

What’s Next?

We’ll start with the most popular and versatile structure of them all. In Lesson 2, we dive deep into Lists!