Data Types & Data Structures

Scalar Types

Python's basic building blocks are immutable scalar types.

int: Integers of arbitrary precision.
float: Double-precision floating point numbers.
str: Unicode strings.
bool: True or False.
None: Represents the absence of a value.

Lists: Ordered & Mutable

Lists are the most versatile data structure in Python.

fruits = ["apple", "banana", "cherry"]
fruits.append("date")     # Add to end
first = fruits[0]         # Indexing
subset = fruits[1:3]       # Slicing

Dictionaries: Key-Value Pairs

Dictionaries provide fast lookups using unique keys.

user = {
    "id": 1,
    "username": "pk",
    "active": True
}

val = user["username"]
user["role"] = "admin"

Tuples: Ordered & Immutable

Use tuples for fixed collections of data that shouldn't change.

point = (10, 20)
x, y = point # Unpacking

Sets: Unique & Unordered

Sets are perfect for removing duplicates and mathematical set operations.

ids = {1, 2, 2, 3} # Results in {1, 2, 3}
is_present = 1 in ids

✅ Practice (15 minutes)

Create a list of 5 integers and print the middle 3 using slicing.
Create a dictionary representing a book (title, author, year).
Add a list of chapters to your book dictionary.
Use a set to find the unique colors in ["red", "blue", "red", "green", "blue"].