10 min read Intermediate Lesson 5 of 11
Part 2 — Building with Functions

Data Structures

Choosing the right data structure transforms slow, unreadable code into blazingly fast systems. Master Python's 4 fundamental collections: Lists, Dicts, Sets, and Tuples.

The Big 4 Python Data Structures

List `[...]` Ordered · Mutable

Dynamic array allowing indexed access and append operations.

users = ["Alice", "Bob", "Charlie"]
Dict `{key: val}` Hash Map · O(1) Lookup

Key-value pairs with instant $O(1)$ search time regardless of size.

user = {"id": 101, "name": "Alice"}
Set `{...}` Unique · Unordered

Eliminates duplicates automatically with lightning-fast membership testing (x in set).

tags = {"python", "web", "ai"}
Tuple `(...)` Immutable · Fixed

Protected against modification, lightweight memory overhead.

point = (1920, 1080)

Quick Summary

  • Use Lists for sequential items, Dicts for key-value lookups, and Sets for deduplication.
  • Next, we explore Files & Persistence to save application data to disk permanently.