Foundations Updated 2026-09 View as Markdown

List Comprehensions

List Comprehensions is a very powerful tool, which creates a new list based on another list, in a single, readable line.

For example, let’s say we need to create a list of integers which specify the length of each word in a certain sentence, but only if the word is not the word “the”.

python

sentence = "the quick brown fox jumps over the lazy dog"
words = sentence.split()
word_lengths = []
for word in words:
      if word != "the":
          word_lengths.append(len(word))
print(words)
print(word_lengths)

Using a list comprehension, we could simplify this process to this notation:

python

sentence = "the quick brown fox jumps over the lazy dog"
words = sentence.split()
word_lengths = [len(word) for word in words if word != "the"]
print(words)
print(word_lengths)

Exercise

Try it

ready

Get the Python agent pack

A battle-tested AGENTS.md, the review checklist, and the failure-mode cheat sheet for Python. One email, then occasional updates when the tooling shifts. No course pitch.

Unsubscribe in one click. We never sell the list. Or just take the AGENTS.md now — no email needed.

List Comprehensions

Try it

Solution

Get the Python agent pack