You can return multiple values from a function in Python.

To do so, return a data structure that contains multiple values, like a list containing the number of miles to run each week.

def miles_to_run(minimum_miles):
   week_1 = minimum_miles + 2
   week_2 = minimum_miles + 4
   week_3 = minimum_miles + 6
   return [week_1, week_2, week_3]
 
print(miles_to_run(2))
# result: [4, 6, 8]

Data structures in Python are used to store collections of data, which can be returned from ?functions. In this article, we’ll explore how to return multiple values from these data structures: tuples, lists, and dictionaries.

Tuples

A tuple is an ordered, immutable sequence. That means, a tuple can’t change.

Use a tuple, for example, to store information about a person: their name, age, and location.

nancy = ("nancy", 55, "chicago")

Here’s how you’d write a function that returns a tuple.

def person():
   return "bob", 32, "boston"
 
print(person())
# result: ('bob', 32, 'boston')

Notice that we didn’t use parentheses in the return statement. That’s because you can return a tuple by separating each item with a comma, as shown in the above example.

“It is actually the comma which makes a tuple, not the parentheses,” the documentation points out. However, parentheses are required with empty tuples or to avoid confusion.

Here’s an example of a function that uses parentheses () to return a tuple.

def person(name, age):
   return (name, age)
print(person("henry", 5))
#result: ('henry', 5)

List

A list is an ordered, mutable sequence. That means, a list can change.

You can use a list to store cities:

cities = ["Boston", "Chicago", "Jacksonville"]

Or test scores:

test_scores = [55, 99, 100, 68, 85, 78]

Take a look at the function below. It returns a list that contains ten numbers.

def ten_numbers():
   numbers = []
   for i in range(1, 11):
       numbers.append(i)
   return numbers
 
print(ten_numbers())
#result: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Here’s another example. This time we pass in several arguments when we call the function.

def miles_ran(week_1, week_2, week_3, week_4):
   return [week_1, week_2, week_3, week_4]
 
monthly_mileage = miles_ran(25, 30, 28, 40)
print(monthly_mileage)
#result: [25, 30, 28, 40]

It’s easy to confuse tuples and lists. After all, both are containers that store objects. However, remember these key differences:

  • Tuples can’t change.
  • Lists can change.

Dictionaries

A dictionary contains key-value pairs wrapped in curly brackets {}. Each “key” has a related “value.” ?

Consider the dictionary of employees below. Each employee name is a “key” and their position is the “value.”

employees = {
   "jack": "engineer",
   "mary": "manager",
   "henry": "writer",
}

Here’s how you’d write a function that returns a dictionary with a key, value pair.

def city_country(city, country):
   location = {}
   location[city] = country
   return location
 
favorite_location = city_country("Boston", "United States")
print(favorite_location)
# result: {'Boston': 'United States'}

In the above example, “Boston” is the key and “United States” is the value. ?

We’ve covered a lot of ground. The key point is this: you can return multiple values from a Python function, and there are several ways to do so.

I write about the programming skills you need to develop and the concepts you need to learn, and the best ways to learn them at amymhaddad.com.