Python! Storing Multiple Values | Lectures 9

Lets Start Python Programming For Beginners to advanced. Lists – Storing Multiple Values, Lectures 9

Table of Contents

🐍 Lecture 9: Lists – Storing Multiple Values

🎯 Goal

By the end of this lecture, you will:

Understand what a list is and why it’s useful.
Be able to create, modify, and access items in a list.
Use common list methods like append(), remove(), and index().
Loop through a list using a for loop.

🧠 What Is a List?

A list is like a container that can hold multiple values at once.
You can think of it as a shopping list or a backpack — it holds many things in order.

🛒 Example:

fruits = ["apple", "banana", "cherry"]

This list contains 3 items , and they stay in the order you put them in.

📦 How to Create a List

Use square brackets [ ] and separate items with commas.

Syntax:

my_list = [item1, item2, item3]

Examples:

numbers = [1, 2, 3, 4, 5]
names = ["Alice", "Bob", "Charlie"]
mixed = [1, "apple", True, 3.14]

🧒 Kids Corner: A list is like your toy box — it can hold many different toys all together!

🔢 Accessing Items in a List

Each item has an index (a number that tells its position).
Indexing starts at 0 , not 1.

fruits = ["apple", "banana", "cherry"]

print(fruits[0])  # Output: apple
print(fruits[1])  # Output: banana
print(fruits[2])  # Output: cherry

You can also use negative indexes to go from the end:

print(fruits[-1])  # Output: cherry
print(fruits[-2])  # Output: banana

✏️ Changing List Items

You can update any item by referring to its index:

fruits = ["apple", "banana", "cherry"]
fruits[1] = "blueberry"
print(fruits)  # Output: ['apple', 'blueberry', 'cherry']

➕ Adding Items to a List

Use .append() to add an item to the end of the list:

fruits = ["apple", "banana"]
fruits.append("orange")
print(fruits)  # Output: ['apple', 'banana', 'orange']

Or use .insert() to add at a specific position:

fruits.insert(1, "grape")
print(fruits)  # Output: ['apple', 'grape', 'banana', 'orange']

➖ Removing Items from a List

Use .remove() to remove a specific value:

fruits.remove("banana")
print(fruits)  # Now banana is gone

Or use del to remove by index:

del fruits[0]
print(fruits)  # First item is gone

Use .pop() to remove and get the last item:

last_fruit = fruits.pop()
print("Removed:", last_fruit)

🔁 Looping Through a List

Use a for loop to do something for each item:

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

👉 Output:

apple
banana
cherry

This is super useful when working with large lists!

🧪 Try It Yourself!

Write code that:

Creates a list of your favorite animals.
Prints out each animal using a for loop.
Adds a new animal to the list.
Removes one animal.
Prints the updated list.

💡 Sample Code:

animals = ["dog", "cat", "elephant"]
print("My favorite animals:")

for animal in animals:
    print(animal)

animals.append("lion")
animals.remove("cat")

print("\nUpdated list:")
print(animals)

🧒 Kids Corner

🧠 Imagine you have a robot friend who loves collecting stickers.
It can keep all its stickers in a special sticker book — that’s what a list is!

🤖 Robot says:

I have 5 stickers: cat, dog, star, car, and rainbow!

🚀 Challenge (Optional)

Make a grocery list app where the user can:

Add an item.
Remove an item.
View the whole list.

Example:

grocery = []

while True:
    action = input("What do you want to do? (add, remove, view, quit): ")

    if action == "add":
        item = input("Enter item to add: ")
        grocery.append(item)
    elif action == "remove":
        item = input("Enter item to remove: ")
        if item in grocery:
            grocery.remove(item)
        else:
            print("Item not found!")
    elif action == "view":
        print("Your list:", grocery)
    elif action == "quit":
        print("Goodbye!")
        break
    else:
        print("Invalid choice!")