Reference library
Lists & loops
Iterate, transform, and combine sequences with readable Python patterns.
List comprehension filter
Build a new list in one line by filtering and transforming items.
numbers = [1, 2, 3, 4, 5, 6, 7, 8]
doubled_evens = [n * 2 for n in numbers if n % 2 == 0]
print(doubled_evens)
names = ["ada", "linus", "guido"]
title_case = [name.title() for name in names if name]
print(title_case)Enumerate with index
Loop with both index and value — cleaner than manual counters.
tasks = ["read docs", "write code", "run tests"]
for i, task in enumerate(tasks, start=1):
print(f"{i}. {task}")Zip two lists
Pair items from parallel lists and iterate them together.
names = ["Ada", "Grace", "Katherine"]
scores = [98, 95, 100]
for name, score in zip(names, scores):
print(f"{name}: {score}")
print(list(zip(names, scores)))Browse by section
Each section groups closely related Python snippets.
Lists & loops — Python code examples
What you will find here
This page collects lists & loops snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.