Languages

Python

Python 3.12 essentials — collections, comprehensions, and idioms.

Data types

x = 42            # int
y = 3.14          # float
s = "text"        # str
flag = True       # bool
nums = [1, 2, 3]  # list
pt = (1, 2)       # tuple
uniq = {1, 2}     # set
m = {"a": 1}      # dict

Comprehensions

squares = [x*x for x in range(10)]
evens = [x for x in nums if x % 2 == 0]
pairs = {k: v for k, v in items}
uniq = {x % 3 for x in nums}
gen = (x*x for x in range(10))   # generator

Strings

s.split(",")To list

",".join(lst)List to string

s.strip()Trim whitespace

s.replace("a","b")Replace

f"{x:.2f}"Format float

s.startswith("x")Prefix check

Dict & list ops

d.get(k, default)Safe lookup

d.items()Key/value pairs

d.setdefault(k, [])Init if missing

lst.append(x)Add to end

lst[::-1]Reverse

sorted(lst, key=fn)Sort by key

enumerate(lst)Index + value

zip(a, b)Pair up

Functions

def greet(name, *args, **kwargs):
    return f"Hi {name}"

add = lambda a, b: a + b

# type hints
def total(items: list[int]) -> int:
    return sum(items)

Control flow

for i, x in enumerate(nums):
    if x > 10: break
    elif x < 0: continue

with open("f.txt") as f:
    data = f.read()

match cmd:
    case "start": ...
    case _: ...      # default

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