Lists & Tuples

Lists and tuples are ordered collections in Python. They're fundamental for AI work—you'll use them to store conversation history, tool results, and much more.

Lists: Mutable Collections

Lists can be modified after creation.

# Creating lists
messages = ["Hello", "How are you?", "I'm fine"]
numbers = [1, 2, 3, 4, 5]
mixed = [1, "text", True, 3.14]

# Accessing elements (0-indexed)
first = messages[0]      # "Hello"
last = messages[-1]      # "I'm fine"

# Slicing
first_two = messages[0:2]  # ["Hello", "How are you?"]

Modifying Lists

messages = ["Hello"]

# Adding elements
messages.append("World")           # ["Hello", "World"]
messages.insert(0, "Start")        # ["Start", "Hello", "World"]

# Removing elements
messages.remove("Start")           # ["Hello", "World"]
popped = messages.pop()            # Returns "World", list is ["Hello"]

# Changing elements
messages[0] = "Hi"                 # ["Hi"]

List Comprehensions

A powerful way to create lists:

# Without comprehension
squares = []
for x in range(5):
    squares.append(x ** 2)

# With comprehension (cleaner!)
squares = [x ** 2 for x in range(5)]  # [0, 1, 4, 9, 16]

# With condition
evens = [x for x in range(10) if x % 2 == 0]  # [0, 2, 4, 6, 8]

Tuples: Immutable Collections

Tuples cannot be modified after creation—useful for fixed data.

# Creating tuples
point = (10, 20)
rgb = (255, 128, 0)

# Accessing (same as lists)
x = point[0]  # 10

# Tuple unpacking
x, y = point  # x=10, y=20
r, g, b = rgb  # r=255, g=128, b=0

When to Use Each

Use Case	Data Structure
Conversation messages	List (changes over time)
API response fields	Tuple (fixed structure)
Tool arguments	List or Tuple
Configuration values	Tuple (shouldn't change)

Next, we'll explore dictionaries for key-value storage. :::