Lists & Tuples

📋 What are Lists?

So far, you've learned to store single values in variables:

name = "Krishna"
age = 16
score = 95.5

But what if you need to store multiple values? That's where lists come in!

🛠️ Creating Lists

There are several ways to create lists in Python:

numbers = [10, 20, 30]

Memory:
List Object → [ref0, ref1, ref2]
                ↓     ↓     ↓
              [10]  [20]  [30]  (actual integer objects)

🎯 Accessing List Elements

Lists are indexed starting from 0. You can access elements using square brackets:

[start:end]   → From start to end-1
[:end]        → From beginning to end-1
[start:]      → From start to end
[:]           → Entire list (copy)
[::step]      → Every step-th item
[::-1]        → Reverse the list

🔧 List Methods - Powerful Operations

Python provides many built-in methods to work with lists:

🔒 Tuples - Immutable Lists

🚀 Coming Up: Advanced List Techniques

# This creates a list with 1 MILLION numbers in memory
big_list = [i for i in range(1000000)]
# Memory used: ~8MB for the list!

📺 Video Resources

Watch these videos to reinforce your understanding of lists and tuples:

🤖 AI Learning Prompts

Use these prompts with AI assistants to deepen your understanding:

Understanding Lists

I'm learning about Python lists. Please help me understand:

1. What's the difference between lists and regular variables? Why use lists?
2. Explain list indexing with positive and negative indices - show me examples
3. How does list slicing work? Show me [start:end:step] with examples
4. What does "mutable" mean? Why is it important for lists?
5. Create 5 practice problems where I need to create and manipulate lists

Use simple language and lots of visual examples!

Mastering List Methods

Help me master Python list methods:

1. Explain the difference between .append(), .extend(), and .insert()
2. When should I use .remove() vs .pop()? Show examples
3. What's the difference between .sort() and sorted()? When to use each?
4. Show me how to use all list methods with a shopping list example
5. Give me 5 coding challenges that practice different list methods

Include lots of before/after examples!

Lists vs Tuples

I need to understand when to use lists vs tuples:

1. What are the key differences between lists and tuples?
2. Why would I choose a tuple over a list? Give me real-world examples
3. How is memory/performance different between lists and tuples?
4. Show me situations where tuples are the better choice
5. Can I convert between lists and tuples? How?

Give me decision-making guidelines!

Advanced Preview Questions

I saw a preview of list comprehensions and generators:

1. Explain the basic syntax of list comprehensions with simple examples
2. When would I use a generator instead of a list? Why does it matter?
3. Show me the performance difference between lists and generators
4. Are list comprehensions always better than loops? When not to use them?
5. What should I focus on learning now to prepare for these advanced topics?

Keep it beginner-friendly - I'm still learning the basics!

✏️ Practice Exercises

Challenge 1: Shopping List Manager

# Shopping List Manager
shopping_list = ["milk", "bread", "eggs"]
print("Starting list:", shopping_list)

# Add items
shopping_list.append("butter")
shopping_list.append("cheese")
print("After adding:", shopping_list)

# Insert at beginning
shopping_list.insert(0, "coffee")
print("After insert:", shopping_list)

# Remove item
shopping_list.remove("bread")
print("After removing bread:", shopping_list)

print(f"\nFinal list has {len(shopping_list)} items: {shopping_list}")

Challenge 2: Temperature Analyzer

# Temperature Analyzer
temperatures = [72, 68, 75, 70, 78, 74, 71]

highest = max(temperatures)
lowest = min(temperatures)
average = sum(temperatures) / len(temperatures)

# Count days above average
above_average = 0
for temp in temperatures:
    if temp > average:
        above_average += 1

# Display results
print("=" * 40)
print("TEMPERATURE ANALYSIS")
print("=" * 40)
print(f"Temperatures: {temperatures}")
print(f"Highest:  {highest}°F")
print(f"Lowest:   {lowest}°F")
print(f"Average:  {average:.1f}°F")
print(f"Days above average: {above_average}")
print("=" * 40)

Challenge 3: Coordinate Storage

# Coordinate Storage
cities = [
    ("Mumbai", 19.0760, 72.8777),
    ("Delhi", 28.7041, 77.1025),
    ("Bangalore", 12.9716, 77.5946)
]

print("CITY COORDINATES")
print("=" * 50)

# Display all cities
for city, lat, lon in cities:
    print(f"{city:12} → Lat: {lat:7.4f}, Lon: {lon:7.4f}")

# Find northernmost city
northernmost = max(cities, key=lambda x: x[1])
print(f"\nNorthernmost: {northernmost[0]} (Lat: {northernmost[1]})")

# Calculate simplified distance (latitude difference)
lat_diff = abs(cities[0][1] - cities[-1][1])
print(f"\nLatitude difference (first to last): {lat_diff:.4f} degrees")

📝 Knowledge Check - Test Your Understanding!

Answer these questions to check your understanding of Chapter 4.