postMay 18, 2026

Python list comprehensions — short, fast, readable

#python#list-comprehension#intermediate

python

rows = [{"name": "alice", "age": 30},
        {"name": "bob",   "age": 17},
        {"name": "carol", "age": 25}]

# extract names of adults
adults = [r["name"] for r in rows if r["age"] >= 18]

print(adults)  # ['alice', 'carol']

A list comprehension builds a new list by transforming each item from another iterable. It is shorter, faster, and more idiomatic than a regular for-loop with append().

In data engineering you transform lists constantly — extract a single field from each record, convert types, filter rows. List comprehensions make this code half the length and easier to scan. Master them and your scripts immediately look more professional.