Built-in functions

Intermediate Python for Developers

George Boorman

Curriculum Manager, DataCamp

What we'll cover

Functions
- Custom functions

Modules

Packages

Functions we know

# Printing
print("Display this as an output")

'Display this as an output'

# Checking data types
type(print)

builtin_function_or_method

# Looping through a range of numbers
for num in range(1, 5):
    print(num)

max() and min()

sales = [125.97, 84.32, 99.78, 154.21, 78.50, 83.67, 111.13]


# Find the largest sale
max(sales)

154.21

# Find the smallest sale
min(sales)

78.5

sum() and round()

sum(sales)

737.5799999999999

# Store total sales
total_sales = sum(sales)


# Round to two decimal places
round(total_sales, 2)

737.58

Nested functions

Call a function then call another function

# Store total sales
total_sales = sum(sales)

# Round to two decimal places
round(total_sales, 2)

737.58

Call a function within a function

# Store total sales
total_sales = round(sum(sales), 2)


# Round to two decimal places
print(total_sales)

737.58

len()

Counts the number of elements

# Count the number of sales
len(sales)

# Calculate average sales
sum(sales) / len(sales)

105.36857142857141

len()

# Length of a string
len("Introduction to Programming for Developers")

# Length of dictionary
len({"a": 1, "b": 2, "c": 3})

Also works with sets and tuples
Does not work with floats, integers, or booleans

sorted()

# Sort the sales list in ascending order
sorted(sales)

[78.5, 83.67, 84.32, 99.78, 111.13, 
 125.97, 154.21]

# Sort a string alphabetically
sorted("George")

['G', 'e', 'e', 'g', 'o', 'r']

help()

# Get information about the sorted() function
help(sorted)

Help on built-in function sorted in module builtins:

sorted(iterable, /, *, key=None, reverse=False)
    Return a new list containing all items from the iterable in ascending order.

    A custom key function can be supplied to customize the sort order, and the
    reverse flag can be set to request the result in descending order.

Works with int, str, {}, [], list, etc.

Benefits of functions

Perform complex tasks with less code

# Find total sales
sum(sales)

737.5799999999999

Benefits of functions

# Find total sales
# Create a variable to increment
sales_count = 0


# Loop through sales
for sale in sales:

    # Increment sales_count by each sale
    sales_count += sale

    print(sales_count)

sum() is reusable, shorter, cleaner, and less prone to errors!

125.97
210.29
310.07
464.28
542.78
626.4499999999999
737.5799999999999

Functions cheat sheet

Function	Returns
`print()`	Display an output, e.g., variable's values
`max()`	Find the largest value in a data structure
`min()`	Find the smallest value in a data structure
`sum()`	Add up all elements in a data structure
`round()`	Trim a float to a specified number of decimal places
`len()`	Count the number of elements in a data structure
`sorted()`	Sort elements in a data structure in ascending order
`help()`	Get information about a function, variable, or value

¹ https://docs.python.org/3/library/functions.html

Let's practice!

Intermediate Python for Developers