07 – Dictionaries & Sets

Lernziele dieses Kapitels

You create dictionaries and safely access values
You use get(), keys(), values() and items() professionally
You use sets for unique values and set operations
You build PyBuddy's user profile as a dictionary

Dictionary Basics

A dictionary is like a phone book or an inventory in a game: every value has a unique name (key). Instead of numeric indexes, you access values by name.

Create: spieler = {"name": "Max", "level": 5}
Access: spieler["name"]
Safe access: spieler.get("name")

# Dictionary erstellen
spieler = {
    "name": "DragonSlayer99",
    "level": 12,
    "klasse": "Magier",
    "hp": 100
}

print(spieler["name"])       # DragonSlayer99
print(spieler.get("level"))  # 12

# Wert ändern
spieler["level"] = 13
spieler["xp"] = 450  # Neuer Schlüssel!

# Löschen
del spieler["klasse"]
print(spieler)

Ausgabe

DragonSlayer99 12 {'name': 'DragonSlayer99', 'level': 13, 'hp': 100, 'xp': 450}

Du kennst bereits JavaScript aus dem JS-Quest. Hier ist der direkte Vergleich:

Python

spieler = {"name": "Max", "level": 5}
print(spieler["name"])
print(spieler.get("level"))

JavaScript

let spieler = { name: "Max", level: 5 };
console.log(spieler.name);
console.log(spieler.level);

Merke: Python dicts are like JavaScript objects. Access in Python is spieler["name"] or .get(), in JS spieler.name or ["name"].

Methods and Nested Dicts

Dictionaries have powerful methods: keys(), values(), items(). And you can nest dictionaries inside each other — perfect for complex data structures like player profiles.

# Dictionary-Methoden
nutzer = {"name": "Anna", "alter": 17, "ort": "Wien"}

print(list(nutzer.keys()))    # ['name', 'alter', 'ort']
print(list(nutzer.values()))  # ['Anna', 17, 'Wien']

# items() liefert Schlüssel-Wert-Paare
for key, value in nutzer.items():
    print(f"{key}: {value}")

# Verschachtelte Dicts
profil = {
    "user": {"name": "Max", "id": 42},
    "stats": {"level": 5, "xp": 1200},
    "badges": ["Newbie", "Coder"]
}
print(profil["stats"]["level"])  # 5

Ausgabe

['name', 'alter', 'ort'] ['Anna', 17, 'Wien'] name: Anna alter: 17 ort: Wien 5

Sets for Unique Values

A set is like a list, but each value occurs only once — duplicates are automatically removed. Sets are perfect for unique collections and set operations.

# Sets erstellen
besucht = {"Paris", "Tokio", "New York", "Paris"}
print(besucht)  # {'Tokio', 'New York', 'Paris'} — keine Duplikate!

# Mengenoperationen
a = {1, 2, 3, 4}
b = {3, 4, 5, 6}

print(a | b)  # Vereinigung: {1, 2, 3, 4, 5, 6}
print(a & b)  # Schnittmenge: {3, 4}
print(a - b)  # Differenz: {1, 2}

# Prüfung
print(3 in a)  # True
print(7 in a)  # False

Ausgabe

{'Tokio', 'New York', 'Paris'} {1, 2, 3, 4, 5, 6} {3, 4} {1, 2} True False

Du kennst bereits JavaScript aus dem JS-Quest. Hier ist der direkte Vergleich:

Python

a = {1, 2, 3}
b = {3, 4, 5}
print(a | b)
print(3 in a)

JavaScript

let a = new Set([1, 2, 3]);
let b = new Set([3, 4, 5]);
let vereinigung = new Set([...a, ...b]);
console.log(vereinigung);
console.log(a.has(3));

Merke: Python has | and & directly as operators for sets. JavaScript uses Set objects and the spread operator ....

Dict Comprehensions

Just like lists, dictionaries also have comprehensions. You create a dictionary in one line — elegant and pythonic.

# Dict Comprehension
namen = ["Anna", "Ben", "Clara"]
laengen = {name: len(name) for name in namen}
print(laengen)  # {'Anna': 4, 'Ben': 3, 'Clara': 5}

# Mit Bedingung
zahlen = [1, 2, 3, 4, 5, 6]
quadrate = {z: z**2 for z in zahlen if z % 2 == 0}
print(quadrate)  # {2: 4, 4: 16, 6: 36}

# Aus zwei Listen
keys = ["a", "b", "c"]
values = [1, 2, 3]
paar = {k: v for k, v in zip(keys, values)}
print(paar)  # {'a': 1, 'b': 2, 'c': 3}

Ausgabe

{'Anna': 4, 'Ben': 3, 'Clara': 5} {2: 4, 4: 16, 6: 36} {'a': 1, 'b': 2, 'c': 3}

Dictionaries in Action: Player Profile

Imagine a complete player profile: name, level, XP, badges and equipment — all in a nested dictionary. This is the data structure that real games use internally.

# Spieler-Profil
spieler = {
    "name": "PyKnight",
    "level": 7,
    "xp": 3400,
    "badges": ["First Blood", "Level 5"],
    "ausruestung": {
        "waffe": "Stahlschwert",
        "ruestung": "Lederpanzer",
        "gold": 150
    }
}

# XP hinzufügen
gewonnen = 500
spieler["xp"] += gewonnen

# Level-Up prüfen
if spieler["xp"] >= 4000:
    spieler["level"] += 1
    spieler["badges"].append(f"Level {spieler['level']}")
    print(f" Level-Up! Du bist jetzt Level {spieler['level']}!")

# Profil anzeigen
print(f"\n  {spieler['name']} — Level {spieler['level']}")
print(f" XP: {spieler['xp']}")
print(f"  Rüstung: {spieler['ausruestung']['ruestung']}")

Ausgabe

Level-Up! Du bist jetzt Level 8! PyKnight — Level 8 XP: 3900 Rüstung: Lederpanzer

Create a dictionary with 3 contacts (name → phone number). Use input() for a search and print the number or "Not found".

Create kontakte.py
Create dictionary with 3 contacts
Ask for name with input()
Use get() with default value

Hinweis: kontakte = {"Anna": "0664/123", "Ben": "0664/456", "Clara": "0664/789"} name = input("Suche: ") print(kontakte.get(name, " Nicht gefunden"))

kontakte = {"Anna": "0664/123", "Ben": "0664/456", "Clara": "0664/789"}
name = input("Suche: ")
print(kontakte.get(name, " Nicht gefunden"))

The user enters a sentence. Count how often each word occurs. Use a dictionary with words as keys and frequencies as values.

Create woerter.py
Read sentence and split into words
Count frequency in dict
Print result

Hinweis: satz = input("Satz: ").lower() woerter = satz.split() haeufigkeit = {} for wort in woerter: haeufigkeit[wort] = haeufigkeit.get(wort, 0) + 1 for wort, anzahl in haeufigkeit.items(): print(f"{wort}: {anzahl}x")

satz = input("Satz: ").lower()
woerter = satz.split()

haeufigkeit = {}
for wort in woerter:
    haeufigkeit[wort] = haeufigkeit.get(wort, 0) + 1

for wort, anzahl in haeufigkeit.items():
    print(f"{wort}: {anzahl}x")

PyBuddy stores name, level, XP and badges in a dictionary. Display the profile formatted and allow adding XP.

Open pybuddy/main.py
Create dictionary profil
Display profile data formatted
Allow XP update with input()

Hinweis: # pybuddy/main.py profil = { "name": "Max", "level": 1, "xp": 0, "badges": ["PyBuddy Nutzer"] } print(f" Profil von {profil['name']}") print(f" Level {profil['level']} | {profil['xp']} XP") print(f"🎖️ Badges: {', '.join(profil['badges'])}") # XP hinzufügen bonus = int(input("Bonus-XP: ")) profil["xp"] += bonus print(f"Neuer XP-Stand: {profil['xp']}")

# pybuddy/main.py
profil = {
    "name": "Max",
    "level": 1,
    "xp": 0,
    "badges": ["PyBuddy Nutzer"]
}

print(f" Profil von {profil['name']}")
print(f" Level {profil['level']} | {profil['xp']} XP")
print(f"🎖️  Badges: {', '.join(profil['badges'])}")

# XP hinzufügen
bonus = int(input("Bonus-XP: "))
profil["xp"] += bonus
print(f"Neuer XP-Stand: {profil['xp']}")

Didactic Break

In Pokémon, every monster is stored as a dictionary: name, type, HP, attack, defense, move list. When you catch a Pokémon, the game simply adds a new dict to your list. You are building the foundations for your own monster collection!

Zusammenfassung

Dictionary = {'key': 'value'} — like a phone book
get(), keys(), values(), items() for access
Sets = {1, 2, 3} — only unique values
Dict comprehensions for elegant creation
Nested dicts for complex data

Dictionaries & Sets

Lernziele dieses Kapitels

Dictionary Basics

Methods and Nested Dicts

Sets for Unique Values

Dict Comprehensions

Dictionaries in Action: Player Profile

Warm-Up: Contact Book

Challenge: Word Frequency

PyBuddy Checkpoint: User Profile

Zusammenfassung