Python Cheatsheet
Modern Python 3.12+ essentials. Covers syntax, collections, comprehensions, and common stdlib.
1 credit
Basics
5 itemsf-string
f"Hello, {name}! {x:.2f}"Walrus
if (n := len(data)) > 10: ...Ternary
x = a if cond else bTruthy check
if not items: (empty list / "" / 0 / None all falsy)Unpack
a, *rest = [1,2,3,4] → a=1, rest=[2,3,4]Collections
6 itemsList comp
[x*2 for x in nums if x > 0]Dict comp
{k: v for k, v in items}Set
{1, 2, 3} / set(list)Zip
for a, b in zip(xs, ys): ...Enumerate
for i, x in enumerate(xs, start=1): ...Merge dicts
{**a, **b} or a | b (3.9+)Functions & types
python
from dataclasses import dataclass
from typing import Iterable
@dataclass
class User:
id: int
name: str
active: bool = True
def sum_active(users: Iterable[User]) -> int:
return sum(1 for u in users if u.active)Stdlib quick wins
6 itemspathlib
from pathlib import Path; Path("x").read_text()json
import json; json.loads(s); json.dumps(obj, indent=2)itertools
chain, groupby, product, combinations, islicefunctools
lru_cache, reduce, partial, cached_propertycollections
Counter, defaultdict, deque, OrderedDictsubprocess
run(["ls"], capture_output=True, text=True, check=True)