How to Return a List in Python

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Returning a list in Python is as simple as using the return statement from within a function, followed by an object of type list. For example: return [1, 2, 3]. This will return a list containing elements 1, 2, and 3.

Return a list directly

Returning a list in Python can be done by simply returning the definition of a list directly, as you can see below:

def foo():
    return ["this", "is", "a", "list"]

print(foo())
Python

Here, we’ve created a function called foo that just returns a list that is defined in-line with the return statement. If we run this, we’ll get the following output:

['this', 'is', 'a', 'list']

Return a list by variable name

We can also return a variable that refers to a list in Python. This is done in basically the same way as the previous example, except we assign the list definition to a variable first before returning it. Obviously, this is just an example to show how the list can be returned, so there’s no benefit to assigning the list to a variable before returning it in the code below. 

def foo():
    bar = ["this", "is", "a", "list"]
    return bar

print(foo())
Python

As you can see, we assigned the same list definition as the first example to a variable named bar and then returned it. Below is the output you’d get:

['this', 'is', 'a', 'list']

As expected, this is the same as just returning the list directly.

Return a list with list comprehension

Another way to return a list from a function in Python is to use list comprehension. This is a way to give Python a sort of recipe for a list rather than explicitly defining each element individually. It’s a very useful technique that can make your code a whole lot more readable than, say, building a list with a for loop, for example.

Here’s how you’d do it:

def foo():
    return [f"test {number}" for number in range(10)]

print(foo())
Python

What our list comprehension above is doing is telling Python to make a range of numbers (using the built in range() function), then take each one and put it into a string with the format "test {number}", where {number} will be replaced with the current number from the range we’re working with.

Here’s the result:

['test 0', 'test 1', 'test 2', 'test 3', 'test 4', 'test 5', 'test 6', 'test 7', 'test 8', 'test 9']

As you can see the range() function gives you by default a range starting with 0 and ending with the number you passed to it, minus one. Our list comprehension worked as expected.

Conclusion

Returning a list in Python is very simple – you can just do it. There’s no special way to return a list. It’s just an object like everything else and can be passed around as such.