Set comprehension

{expression for item in iterable if condition}

emails = ["[email protected]", "[email protected]", "[email protected]", "[email protected]"]
unique_lower = {e.lower() for e in emails}
print(unique_lower)

{'[email protected]', '[email protected]', '[email protected]'}

Note Set comprehensions automatically deduplicate results. Useful for extracting unique transformed values from a collection.

{expr for item in iterable if cond}

sentence = "the quick brown fox jumps over the lazy dog"
word_lengths = {len(word) for word in sentence.split()}
print(sorted(word_lengths))

[3, 4, 5]

Note Set comprehensions look like dict comprehensions but without the colon. They automatically deduplicate results.