Course Content

Introduction to Python (copy)

1. Getting Started

First Steps Comments Simple Math: Add & Subtract Simple Math: Multiply & Divide Recap

2. Variables and Types

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

3. Conditional Statements

Boolean Data Type Combining Conditions Challenge: Boolean Logic Membership Operators and Type Comparisons Conditional Expressions Challenge: Product Management Capstone Recap

4. Other Data Types

Lists and List Methods Nested Lists Challenge: List Management Tuples and Tuple Methods Tuple Operations Challenge: Tuple Operations Dictionaries and Dictionary Methods Challenge: Pricing Adjustment Capstone Recap

5. Loops

For Loops While Loops Range Function Iterating Over Indexes Challenge: Sales and Shipments Nested Loops Challenge: Automating Stock Control Challenge: Solo Coding Capstone Recap

6. Functions

Built-in Functions Challenge: Zip and Sort Functions User Defined Functions List Behavior in Functions Functions with no Return Modifying Functions Challenge: Product Revenues Capstone Recap

User Defined Functions

A user-defined function is a block of code that you create to perform a specific task. Unlike built-in functions, which are provided by Python, user-defined functions are written by you to solve specific problems in your programs. Once defined, these functions can be reused multiple times, making your code more organized, efficient, and easier to maintain.

Now, let's watch as Alex demonstrates how to create and use user-defined functions to simplify tasks:

The basic structure of a user-defined function in Python looks like this:

python

def: this keyword is used to start the definition of a function;
function_name: this is the name you give to your function. It should be descriptive of what the function does, making your code more readable;
argument_1, argument_2: these are the names of the variables that you pass into the function. They act as placeholders for the values that you'll provide when calling the function. A function can have zero or more parameters;
The colon : signifies the start of the function's code block;
# Code block: this is the body of the function, where you write the code that the function will execute. It must be indented just like when writing loops or conditional statements;
return: this statement is used to exit the function and return a result. Not all functions need a return statement, but it's useful when you want to send a value back to where the function was called.

Parameters and Arguments

Parameters are the variables listed inside the parentheses in the function definition. They are used to receive values (arguments) that are passed into the function.

Arguments are the actual values you provide to the function when you call it. These values are assigned to the function's parameters.


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def greet_customer(name):
    print(f"Hello, {name}! Welcome to our store.")

greet_customer("Alice")

Note

In the example above, name is the parameter, and the string "Alice" is the argument.

Void Functions

As shown above, not all functions need to return a value. Some functions perform a task but don't return anything to the caller. These are known as void functions.

In Python, a void function is a user-defined function that either lacks a return statement or has a return statement that doesn't return any value. In both cases, the function will return None by default.

In the example above, greet_customer() is a void function because it performs the action of printing a greeting but doesn't return any result that can be stored or used elsewhere in the program.

Void Function Example

Here's another example of a void function where the return statement is used to terminate the function's execution but still doesn't return any value.


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# Function to check stock levels of grocery items
def check_stock(inventory):
    for item, stock in inventory.items():
        if stock < 10:
            print(f"Warning: {item} is running low on stock with only {stock} units left!")
            print("Please restock the item before proceeding with the check.")
            return  # Stops the function if stock is below 10
        print(f"{item} has sufficient stock: {stock} units.")
    
    print("All items have sufficient stock.")

# Example inventory of a grocery store
inventory = {
    "Apples": 50,
    "Bananas": 30,
    "Milk": 8,  # This will trigger the early exit
    "Bread": 25
}

# Check stock levels
check_stock(inventory)

Example Application

Now, let's consider a function that returns a specific value. For example, if you often need to calculate discounts for different products in your store, you can create a function to perform the discount calculation. This function can then be reused whenever necessary.


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# `cost` and `discount_rate` are the parameters of the function
def calculate_discounted_price(cost, discount_rate):
    final_price = cost * (1 - discount_rate)
    return final_price

# Call the `calculate_discounted_price` function and pass in `cost` and `discount_rate` values as arguments
apples_final_price = calculate_discounted_price(1.2, 0.10)
milk_final_price = calculate_discounted_price(2.2, 0.15)
bread_final_price = calculate_discounted_price(0.8, 0.05)

# Display the discounted prices
print(f"The discounted price of apples is ${apples_final_price}")
print(f"The discounted price of milk is ${milk_final_price}")
print(f"The discounted price of bread is ${bread_final_price}")

Task

Swipe to start coding

Define a function to calculate the total cost of a product by multiplying its price and quantity sold.

Create a function called calculate_total_cost() that takes two parameters: price and quantity.
Inside the function, multiply price by quantity to get the total cost.
Return the result from the function.

Output Requirements

Call calculate_total_cost() with price = 1.50 and quantity = 10.
Print the result as:
The total cost for apples is $<apples_total_cost>

Solution

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

Everything was clear?

Thanks for your feedback!

Section 6. Chapter 3

User Defined Functions

Now, let's watch as Alex demonstrates how to create and use user-defined functions to simplify tasks:

The basic structure of a user-defined function in Python looks like this:

python

def: this keyword is used to start the definition of a function;
function_name: this is the name you give to your function. It should be descriptive of what the function does, making your code more readable;
argument_1, argument_2: these are the names of the variables that you pass into the function. They act as placeholders for the values that you'll provide when calling the function. A function can have zero or more parameters;
The colon : signifies the start of the function's code block;
# Code block: this is the body of the function, where you write the code that the function will execute. It must be indented just like when writing loops or conditional statements;
return: this statement is used to exit the function and return a result. Not all functions need a return statement, but it's useful when you want to send a value back to where the function was called.

Parameters and Arguments

Parameters are the variables listed inside the parentheses in the function definition. They are used to receive values (arguments) that are passed into the function.

Arguments are the actual values you provide to the function when you call it. These values are assigned to the function's parameters.


              1234
            
def greet_customer(name):
    print(f"Hello, {name}! Welcome to our store.")

greet_customer("Alice")

Note

In the example above, name is the parameter, and the string "Alice" is the argument.

Void Functions

As shown above, not all functions need to return a value. Some functions perform a task but don't return anything to the caller. These are known as void functions.

Void Function Example

Here's another example of a void function where the return statement is used to terminate the function's execution but still doesn't return any value.


              123456789101112131415161718192021
            
# Function to check stock levels of grocery items
def check_stock(inventory):
    for item, stock in inventory.items():
        if stock < 10:
            print(f"Warning: {item} is running low on stock with only {stock} units left!")
            print("Please restock the item before proceeding with the check.")
            return  # Stops the function if stock is below 10
        print(f"{item} has sufficient stock: {stock} units.")
    
    print("All items have sufficient stock.")

# Example inventory of a grocery store
inventory = {
    "Apples": 50,
    "Bananas": 30,
    "Milk": 8,  # This will trigger the early exit
    "Bread": 25
}

# Check stock levels
check_stock(inventory)

Example Application


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# `cost` and `discount_rate` are the parameters of the function
def calculate_discounted_price(cost, discount_rate):
    final_price = cost * (1 - discount_rate)
    return final_price

# Call the `calculate_discounted_price` function and pass in `cost` and `discount_rate` values as arguments
apples_final_price = calculate_discounted_price(1.2, 0.10)
milk_final_price = calculate_discounted_price(2.2, 0.15)
bread_final_price = calculate_discounted_price(0.8, 0.05)

# Display the discounted prices
print(f"The discounted price of apples is ${apples_final_price}")
print(f"The discounted price of milk is ${milk_final_price}")
print(f"The discounted price of bread is ${bread_final_price}")

Task

Swipe to start coding

Define a function to calculate the total cost of a product by multiplying its price and quantity sold.

Create a function called calculate_total_cost() that takes two parameters: price and quantity.
Inside the function, multiply price by quantity to get the total cost.
Return the result from the function.

Output Requirements

Call calculate_total_cost() with price = 1.50 and quantity = 10.
Print the result as:
The total cost for apples is $<apples_total_cost>

Solution

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

Everything was clear?

Thanks for your feedback!

Section 6. Chapter 3

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