Defining a custom function

Intermediate Python for Developers

Jasmin Ludolf

Senior Data Science Content Developer

Calculating the average

# List of preparation times (minutes)
preparation_times = [19.23, 15.67, 48.57, 23.45, 12.06, 34.56, 45.67]


# Calculating average preparation time
average_time = sum(preparation_times) / len(preparation_times)


# Rounding the results
rounded_average_time = round(average_time, 2)
print(average_time)

28.46

When to make a custom function

Don't Repeat Yourself (DRY)

Considerations for making a custom function:
- Number of lines
- Code complexity
- Frequency of use

Desert

Creating a custom function

# Create a custom function to calculate the average value
def

Creating a custom function

# Create a custom function to calculate the average value
def average

Creating a custom function

# Create a custom function to calculate the average value
def average(

Creating a custom function

# Create a custom function to calculate the average value
def average(values)

values (argument) - information the function needs to do its job

Creating a custom function

# Create a custom function to calculate the average value
def average(values):

Creating a custom function

# Create a custom function to calculate the average value
def average(values):
    # Calculate the average
    average_value = sum(values) / len(values)

Creating a custom function

# Create a custom function to calculate the average value
def average(values):
    # Calculate the average
    average_value = sum(values) / len(values)

    # Round the results
    rounded_average = round(average_value, 2)

Creating a custom function

# Create a custom function to calculate the average value
def average(values):
    # Calculate the average
    average_value = sum(values) / len(values)

    # Round the results
    rounded_average = round(average_value, 2)


    # Return an output
    return

average_value and rounded_average are only available within average()

Creating a custom function

# Create a custom function to calculate the average value
def average(values):
    # Calculate the average
    average_value = sum(values) / len(values)

    # Round the results
    rounded_average = round(average_value, 2)

    # Return rounded_average as an output
    return rounded_average

Documentation is essential 📚

Using a custom function

# List of preparation times (minutes)
preparation_times = [19.23, 15.67, 48.57, 23.45, 12.06, 34.56, 45.67]


# Calculating the average
print(average(preparation_times))

28.46

# List of orders
orders = [12, 8, 10, 9, 15, 21, 16]

print(average(orders))

12.86

Storing a function's output

# Calculating the average
print(average(preparation_times))

28.46

# Storing average_time
average_time = average(preparation_times)

print(average_time)

28.46

Let's practice!

Intermediate Python for Developers