Course Content

Introduction to Python Video Course

1. Getting Started

First Steps Comments Simple Math Operations Grocery Calculation Capstone Recap

2. Variables and Types

Data Types Storing Data in Variables Variable Naming Rules Using Variables String Indexing and Length String Slicing and Concatenation Inventory Sorting Capstone Challenge Recap

3. Conditional Statements

Boolean Data Type Combining Conditions Challenge Membership Operators and Type Comparisons Conditional Expressions Capstone Challenge Recap

4. Other Data Types

Lists and List Methods Nested Lists Challenge Tuples and Tuple Methods Tuple Operations Challenge Dictionaries and Dictionary Methods Capstone Challenge Recap

5. Loops

For Loops While Loops Range Function Iterating Over Indexes Challenge Nested Loops Capstone Challenge Challenge Recap

6. Functions

Built-in Functions User Defined Functions Challenge Functions with no `return`Modifying Functions Capstone Challenge Recap

Iterating Over Indexes

Index iteration is a fundamental technique in Python, enabling you to access and manipulate elements directly by their positions within data structures like lists or arrays. This approach is particularly useful for tasks that require precise control over sequence elements, such as adjusting inventory levels or processing sales data in a grocery store.

Watch as Alex demonstrates the power and utility of iterating over indexes to streamline operations in our grocery store scenario:

Iterating over indexes is useful when you need to access both the index and the value of each element in a list. When we use range() with len(), we are combining two functions to generate a sequence of numbers corresponding to the indices of the list elements. This method is particularly useful in loops where you need to access or modify elements based on their position.

For example, this for loop accesses the index and the value of each element in the grocery_list:


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# List of grocery items
grocery_list = ["Apples", "Bananas", "Carrots", "Dates"]

# Initialize a for loop to iterate over indexes
for item in range(len(grocery_list)):
    print("Index:", item)
    print("Item:", grocery_list[item])
    print("----")  # Separator for clarity

Example Application

To apply a discount to a list of prices, we need to modify the elements of the list directly. Using a simple loop like for cost in prices: would only give us a copy of each item, not a reference to the actual item in the list. Modifications made in this manner would not affect the original list. To ensure we directly update each element in the prices list, we use range(len(prices)) to iterate over the indices. This allows us to apply a discount factor to each element:


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# List of original prices of grocery items
prices = [1.50, 2.00, 0.75, 3.25]

# Discount factor (10% off each item)
discount_factor = 0.10

# Iterate over the list of prices using range(len())
for cost in range(len(prices)):
    # Apply the discount by reducing the price
    prices[cost] -= prices[cost] * discount_factor
    print(f"New price of item {cost+1}: ${prices[cost]}")
print("")
print("Updated prices:", prices)

This method ensures that the original list prices is updated directly with the new, discounted prices, reflecting the changes immediately across the program wherever the prices list is used.

Task

You were given a list of tuples, where each tuple contains an item's name and its current stock, you'll use index iteration to update stock levels and determine if reordering is necessary based on a minimum stock threshold.

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Section 5. Chapter 4

Iterating Over Indexes

Watch as Alex demonstrates the power and utility of iterating over indexes to streamline operations in our grocery store scenario:

For example, this for loop accesses the index and the value of each element in the grocery_list:


              12345678
            
# List of grocery items
grocery_list = ["Apples", "Bananas", "Carrots", "Dates"]

# Initialize a for loop to iterate over indexes
for item in range(len(grocery_list)):
    print("Index:", item)
    print("Item:", grocery_list[item])
    print("----")  # Separator for clarity

Example Application


              12345678910111213
            
# List of original prices of grocery items
prices = [1.50, 2.00, 0.75, 3.25]

# Discount factor (10% off each item)
discount_factor = 0.10

# Iterate over the list of prices using range(len())
for cost in range(len(prices)):
    # Apply the discount by reducing the price
    prices[cost] -= prices[cost] * discount_factor
    print(f"New price of item {cost+1}: ${prices[cost]}")
print("")
print("Updated prices:", prices)

This method ensures that the original list prices is updated directly with the new, discounted prices, reflecting the changes immediately across the program wherever the prices list is used.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Section 5. Chapter 4

Iterating Over Indexes

Watch as Alex demonstrates the power and utility of iterating over indexes to streamline operations in our grocery store scenario:

For example, this for loop accesses the index and the value of each element in the grocery_list:


              12345678
            
# List of grocery items
grocery_list = ["Apples", "Bananas", "Carrots", "Dates"]

# Initialize a for loop to iterate over indexes
for item in range(len(grocery_list)):
    print("Index:", item)
    print("Item:", grocery_list[item])
    print("----")  # Separator for clarity

Example Application


              12345678910111213
            
# List of original prices of grocery items
prices = [1.50, 2.00, 0.75, 3.25]

# Discount factor (10% off each item)
discount_factor = 0.10

# Iterate over the list of prices using range(len())
for cost in range(len(prices)):
    # Apply the discount by reducing the price
    prices[cost] -= prices[cost] * discount_factor
    print(f"New price of item {cost+1}: ${prices[cost]}")
print("")
print("Updated prices:", prices)

This method ensures that the original list prices is updated directly with the new, discounted prices, reflecting the changes immediately across the program wherever the prices list is used.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Watch as Alex demonstrates the power and utility of iterating over indexes to streamline operations in our grocery store scenario:

For example, this for loop accesses the index and the value of each element in the grocery_list:


              12345678
            
# List of grocery items
grocery_list = ["Apples", "Bananas", "Carrots", "Dates"]

# Initialize a for loop to iterate over indexes
for item in range(len(grocery_list)):
    print("Index:", item)
    print("Item:", grocery_list[item])
    print("----")  # Separator for clarity

Example Application


              12345678910111213
            
# List of original prices of grocery items
prices = [1.50, 2.00, 0.75, 3.25]

# Discount factor (10% off each item)
discount_factor = 0.10

# Iterate over the list of prices using range(len())
for cost in range(len(prices)):
    # Apply the discount by reducing the price
    prices[cost] -= prices[cost] * discount_factor
    print(f"New price of item {cost+1}: ${prices[cost]}")
print("")
print("Updated prices:", prices)

This method ensures that the original list prices is updated directly with the new, discounted prices, reflecting the changes immediately across the program wherever the prices list is used.

Task

Task: Iterate Over Indexes: Use a for loop with range() and len() to iterate over the stock_items list by index.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Section 5. Chapter 4

Switch to desktop for real-world practiceContinue from where you are using one of the options below