Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.Learn Modifying Functions | Functions
Introduction to Python

Swipe to show menu

book
Modifying Functions

In programming, functions are dynamic tools that can adapt to different situations and needs. They're not just fixed blocks of code. You can enhance functions to make them more versatile and user-friendly in various contexts.

In this chapter, we'll explore some important techniques for modifying functions, like using default arguments and keyword arguments.

Let's start with a straightforward example of modifying functions to improve their usefulness in our grocery store management system:

Default Arguments

Default arguments are a useful feature in Python that allow you to specify default values for function parameters.

In the apply_discount() function, the discount parameter is set to 0.10 by default. This means the function will automatically apply a 10% discount unless otherwise specified. As seen in the default_discount_price variable, we can call the function with just the price parameter.

However, if needed, we can override the default value by passing both the price and a custom discount (e.g., 0.20 for 20%) as demonstrated with the custom_discount_price variable.


              
123456789101112

            
# Define a function with a default `discount` argument
def apply_discount(price, discount=0.10):
    discounted_price = price * (1 - discount)
    return discounted_price

# Call the function without providing a `discount`, using the default value
default_discount_price = apply_discount(100)
print(f"Price after applying the default discount: ${default_discount_price}")

# Call the function with a custom `discount` value
custom_discount_price = apply_discount(100, 0.20)
print(f"Price after applying a custom discount: ${custom_discount_price}")
copy

Keyword Arguments

Keyword arguments in Python allow you to pass arguments by explicitly naming each parameter, making your function calls more readable and flexible. This is particularly helpful when a function has multiple parameters or when the order of arguments could be confusing.

In the following example, both price and discount are specified, while the tax parameter remains at its default value, providing flexibility without compromising clarity.


              
12345678

            
# Function where `tax` has a default value
def calculate_total(price, discount, tax=0.05):
    total = price * (1 + tax) * (1 - discount)
    return total

# Calling the function using keyword arguments
total_cost = calculate_total(price=100, discount=0.15)
print(f"Total cost after applying discount: ${total_cost}")
copy

Note

The order of parameters doesn't matter when they are passed using keyword arguments.

Task

Swipe to start coding

Create functions to calculate the total cost of a product by applying a discount and tax, using keyword arguments and default values for flexibility.

  • Define apply_discount(price, discount=0.05)
    β†’ Returns the price after applying the discount.
  • Define apply_tax(price, tax=0.07)
    β†’ Returns the price after adding the tax.
  • Define calculate_total(price, discount=0.05, tax=0.07)
    β†’ Uses apply_discount() and apply_tax() to return the total price with both discount and tax applied.
  • Call calculate_total(120) using the default discount and tax.
  • Call calculate_total(100, discount=0.10, tax=0.08) using custom values via keyword arguments.

Output Requirements

  • Print the result with default values:
    Total cost with default discount and tax: $<total_price_default>
  • Print the result with custom values:
    Total cost with custom discount and tax: $<total_price_custom>

Note

When defining functions, place required parameters first, followed by parameters with default values.

When calling functions with keyword arguments, positional arguments should come before keyword arguments.

Solution

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 6. ChapterΒ 6

Ask AI

expand
ChatGPT

Ask anything or try one of the suggested questions to begin our chat

book
Modifying Functions

In programming, functions are dynamic tools that can adapt to different situations and needs. They're not just fixed blocks of code. You can enhance functions to make them more versatile and user-friendly in various contexts.

In this chapter, we'll explore some important techniques for modifying functions, like using default arguments and keyword arguments.

Let's start with a straightforward example of modifying functions to improve their usefulness in our grocery store management system:

Default Arguments

Default arguments are a useful feature in Python that allow you to specify default values for function parameters.

In the apply_discount() function, the discount parameter is set to 0.10 by default. This means the function will automatically apply a 10% discount unless otherwise specified. As seen in the default_discount_price variable, we can call the function with just the price parameter.

However, if needed, we can override the default value by passing both the price and a custom discount (e.g., 0.20 for 20%) as demonstrated with the custom_discount_price variable.


              
123456789101112

            
# Define a function with a default `discount` argument
def apply_discount(price, discount=0.10):
    discounted_price = price * (1 - discount)
    return discounted_price

# Call the function without providing a `discount`, using the default value
default_discount_price = apply_discount(100)
print(f"Price after applying the default discount: ${default_discount_price}")

# Call the function with a custom `discount` value
custom_discount_price = apply_discount(100, 0.20)
print(f"Price after applying a custom discount: ${custom_discount_price}")
copy

Keyword Arguments

Keyword arguments in Python allow you to pass arguments by explicitly naming each parameter, making your function calls more readable and flexible. This is particularly helpful when a function has multiple parameters or when the order of arguments could be confusing.

In the following example, both price and discount are specified, while the tax parameter remains at its default value, providing flexibility without compromising clarity.


              
12345678

            
# Function where `tax` has a default value
def calculate_total(price, discount, tax=0.05):
    total = price * (1 + tax) * (1 - discount)
    return total

# Calling the function using keyword arguments
total_cost = calculate_total(price=100, discount=0.15)
print(f"Total cost after applying discount: ${total_cost}")
copy

Note

The order of parameters doesn't matter when they are passed using keyword arguments.

Task

Swipe to start coding

Create functions to calculate the total cost of a product by applying a discount and tax, using keyword arguments and default values for flexibility.

  • Define apply_discount(price, discount=0.05)
    β†’ Returns the price after applying the discount.
  • Define apply_tax(price, tax=0.07)
    β†’ Returns the price after adding the tax.
  • Define calculate_total(price, discount=0.05, tax=0.07)
    β†’ Uses apply_discount() and apply_tax() to return the total price with both discount and tax applied.
  • Call calculate_total(120) using the default discount and tax.
  • Call calculate_total(100, discount=0.10, tax=0.08) using custom values via keyword arguments.

Output Requirements

  • Print the result with default values:
    Total cost with default discount and tax: $<total_price_default>
  • Print the result with custom values:
    Total cost with custom discount and tax: $<total_price_custom>

Note

When defining functions, place required parameters first, followed by parameters with default values.

When calling functions with keyword arguments, positional arguments should come before keyword arguments.

Solution

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 6. ChapterΒ 6
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
We're sorry to hear that something went wrong. What happened?
some-alt