Lesson 1 — Comprehensions with a filter

Concise loops

A comprehension builds a list in one line: [expr for x in items if cond]. The expression decides what goes in, the for part says where items come from, and the optional if part keeps only the items that pass. Python reads it left to right, just like the loop it replaces.

names = ["ann", "bob", "al"]
short = [n for n in names if len(n) < 3]
print(short)  # ['al']

Why it matters: filtering and transforming lists is daily work, and comprehensions make it short and readable.