Die Standardbibliothek im Überblick

from collections import Counter, defaultdict, deque, namedtuple

# Counter zählt
print(Counter("mississippi"))
print(Counter("a b a c a b".split()).most_common(2))

# defaultdict legt fehlende Schlüssel selbst an
gruppen = defaultdict(list)
for wort in ["Apfel", "Ananas", "Birne", "Banane", "Kirsche"]:
    gruppen[wort[0]].append(wort)
print(dict(gruppen))

# deque: schnelle Warteschlange
q = deque([1, 2, 3])
q.append(4)
q.appendleft(0)
print(q.popleft(), list(q))

# namedtuple: Tupel mit Feldnamen
Punkt = namedtuple("Punkt", ["x", "y"])
p = Punkt(3, 4)
print(p.x, p.y, p)

import statistics as st
werte = [2, 4, 4, 4, 5, 5, 7, 9]
print(st.mean(werte))
print(st.median(werte))
print(st.mode(werte))
print(round(st.stdev(werte), 3))

import os, sys

print(type(os.getcwd()))            # aktuelles Arbeitsverzeichnis
print(os.path.join("ordner", "datei.txt"))
print(os.path.splitext("bild.png"))
print(sys.version_info >= (3, 8))
print(len(sys.argv))                # Argumente: [Skriptname, ...]

import textwrap, string, pprint

print(textwrap.fill("Python bringt viele nützliche Module mit.", width=20))
print(string.ascii_lowercase[:5], string.digits)
pprint.pprint({"name": "Mia", "hobbys": ["Lesen", "Rad", "Kochen"], "alter": 17}, width=30)

import sqlite3

db = sqlite3.connect(":memory:")
db.execute("CREATE TABLE tiere (name TEXT, beine INTEGER)")
db.executemany("INSERT INTO tiere VALUES (?, ?)", [("Hund", 4), ("Vogel", 2), ("Spinne", 8)])
for zeile in db.execute("SELECT name FROM tiere WHERE beine > 3 ORDER BY name"):
    print(zeile[0])
db.close()

import math
print(math.hypot.__doc__.splitlines()[0])