List Comprehensions: Your Build-a-List Loop in One Line

How does the four-line create-loop-append-return pattern collapse into a single bracketed expression — and where does the filter go?

Finger exercises

Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.

0 / 5 passed

Exercise 1 of 5

Here is the long way to build a list, written out in full:

result = []
for e in numbers:
    result.append(e * 3)

Build that exact same list in one line with a list comprehension over numbers. Assign it to tripled.

# Build the same list the loop above builds, in a single line.
numbers = [2, 3, 5, 7]

tripled = ...  # your code here

# Build the same list the loop above builds, in a single line.
numbers = [2, 3, 5, 7]

tripled = ...  # your code here

Python runs in your browser

⌘/Ctrl + Enter runs

is a list

has one entry per number in the input

holds the same values the loop would append