Python Crash Course

Recap Kapitel 1-8

Wiederholung & Vorbereitung auf Funktionen

Alles Wichtige aus den ersten 8 Kapiteln

Was haben wir gelernt? 📚

• Kapitel 1: Python installieren & erste Programme
• Kapitel 2: Variablen & Datentypen
• Kapitel 3: Listen einführen
• Kapitel 4: Mit Listen arbeiten (for-Schleifen)
• Kapitel 5: if-Anweisungen & Bedingungen
• Kapitel 6: Dictionaries
• Kapitel 7: Benutzereingaben & while-Schleifen
• Kapitel 8: Funktionen (Preview)

Kapitel 1: Erste Schritte 🚀

• Python installieren und IDE einrichten
• Erstes "Hello World!" Programm
• Python-Syntax Grundlagen

print("Hello, World!")
print("Hello Python world!")

# Das war unser erstes Programm!

Kapitel 2: Variablen & Datentypen 📦

name = "Ada Lovelace"
message = f"Hello, {name}!"
print(message.upper())
print(message.lower())
print(message.title())

age = 23
temperature = 17.5

# Rechnen
result = 2 + 3 * 4
print(2 ** 3)  # 8
print(17 / 5)  # 3.4
print(17 // 5) # 3

Kapitel 3: Listen Grundlagen 📝

# Liste erstellen
bicycles = ['trek', 'cannondale', 'redline', 'specialized']

# Zugriff auf Elemente
print(bicycles[0])   # 'trek'
print(bicycles[-1])  # 'specialized'

# Listen ändern
bicycles[0] = 'giant'
bicycles.append('scott')
bicycles.insert(1, 'cube')
bicycles.remove('redline')

print(len(bicycles))  # Anzahl Elemente

Kapitel 4: for-Schleifen 🔄

# for-Schleife
magicians = ['alice', 'david', 'carolina']
for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")
    print(f"{magician.title()}, I can't wait to see your next trick!")

print("Thank you, everyone. That was a great magic show!")

range() & Listen-Generierung 🔢

# range() verwenden
for value in range(1, 5):
    print(value)  # 1, 2, 3, 4

# Listen mit range()
numbers = list(range(1, 6))  # [1, 2, 3, 4, 5]
even_numbers = list(range(2, 11, 2))  # [2, 4, 6, 8, 10]

# List Comprehensions
squares = [value**2 for value in range(1, 11)]
print(squares[:5])  # [1, 4, 9, 16, 25]

Listen-Statistiken 📊

digits = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]

# Statistische Funktionen
print(f"Minimum: {min(digits)}")     # 0
print(f"Maximum: {max(digits)}")     # 9
print(f"Summe: {sum(digits)}")       # 45
print(f"Anzahl: {len(digits)}")      # 10

# Noch mehr Statistiken
print(f"Durchschnitt: {sum(digits)/len(digits):.1f}")  # 4.5

Listen-Slicing 🔪

players = ['charles', 'martina', 'michael', 'florence', 'eli']

# Slicing
print(players[0:3])    # ['charles', 'martina', 'michael']
print(players[1:4])    # ['martina', 'michael', 'florence']
print(players[:4])     # Erste 4
print(players[2:])     # Ab Index 2
print(players[-3:])    # Letzte 3

# Kopien von Listen
my_foods = ['pizza', 'falafel', 'carrot cake']
friend_foods = my_foods[:]    # Kopie!
# nicht: friend_foods = my_foods  # Das wäre nur eine Referenz

Kapitel 5: if-Anweisungen Basics ⚖️

age = 19

# Einfache if-Anweisung
if age >= 18:
    print("You are old enough to vote!")
else:
    print("Sorry, you are too young to vote.")
    print("Please register to vote as soon as you turn 18!")

if-elif-else Ketten 🔗

# Mehrere Bedingungen
age = 12

if age < 4:
    price = 0
elif age < 18:
    price = 5
elif age < 65:
    price = 10
else:
    price = 5

print(f"Your admission cost is ${price}.")

Listen mit if testen 📝

requested_toppings = ['mushrooms', 'extra cheese']

# Einzelne Werte prüfen
if 'mushrooms' in requested_toppings:
    print("Adding mushrooms.")
if 'pepperoni' in requested_toppings:
    print("Adding pepperoni.")
if 'extra cheese' in requested_toppings:
    print("Adding extra cheese.")

print("\nFinished making your pizza!")

Vergleichsoperatoren 🧠

# Gleichheit und Ungleichheit
print(5 == 5)    # True
print(5 != 3)    # True

# Größer/kleiner
print(5 > 3)     # True
print(5 < 3)     # False
print(5 >= 5)    # True
print(4 <= 3)    # False

Logische Operatoren: and, or, not 🔗

age_0 = 22
age_1 = 18

# and: beide Bedingungen müssen True sein
print(age_0 >= 21 and age_1 >= 21)  # False

# or: eine Bedingung muss True sein
print(age_0 >= 21 or age_1 >= 21)   # True

# not: kehrt Boolean-Wert um
print(not age_0 < 18)  # True

in und not in Operatoren 📋

# Listen testen
users = ['admin', 'guest', 'user']

print('admin' in users)     # True
print('root' in users)      # False
print('root' not in users)  # True

# Mit Strings
word = "hello"
print('e' in word)      # True
print('x' not in word)  # True

# Boolean Werte
game_active = True
can_edit = False

Kapitel 6: Dictionaries 🗝️

# Dictionary erstellen
alien_0 = {'color': 'green', 'points': 5}

# Werte abrufen
print(alien_0['color'])
print(alien_0.get('color'))
print(alien_0.get('speed', 'No speed value assigned'))

# Hinzufügen und Ändern
alien_0['x_position'] = 0
alien_0['y_position'] = 25
alien_0['speed'] = 'medium'

print(alien_0)

# Werte löschen
del alien_0['points']

Dictionary .items() - Schlüssel & Werte 🔄

user_0 = {
    'username': 'efermi',
    'first': 'enrico',
    'last': 'fermi',
}

# Durch Schlüssel-Wert-Paare iterieren
for key, value in user_0.items():
    print(f"Key: {key}")
    print(f"Value: {value}")

Dictionary .keys() und .values() 🗝️

user_0 = {
    'username': 'efermi',
    'first': 'enrico',
    'last': 'fermi',
}

# Nur Schlüssel
print("Schlüssel:")
for key in user_0.keys():
    print(f"- {key}")

# Nur Werte  
print("\nWerte:")
for value in user_0.values():
    print(f"- {value.title()}")

Verschachtelte Strukturen 📦

# Liste von Dictionaries
users = [
    {'username': 'efermi', 'first': 'enrico', 'last': 'fermi'},
    {'username': 'mcurie', 'first': 'marie', 'last': 'curie'}
]

# Durch verschachtelte Struktur iterieren
for user in users:
    print(f"\nBenutzer: {user['username']}")
    print(f"Name: {user['first'].title()} {user['last'].title()}")

Kapitel 7: Benutzereingaben ⌨️

# input() Funktion
name = input("Please enter your name: ")
print(f"Hello, {name}!")

# Zahlen eingeben (wichtig: int() verwenden!)
age = int(input("How old are you? "))

if age >= 18:
    print("You can vote!")
else:
    print(f"In {18-age} years you can vote!")

while-Schleifen Grundlagen 🔄

# Einfache while-Schleife
current_number = 1
while current_number <= 5:
    print(current_number)
    current_number += 1

# Countdown
countdown = 10
while countdown > 0:
    print(f"Countdown: {countdown}")
    countdown -= 1
print("Start!")

break & continue in while-Schleifen 🚪

# Mit break
while True:
    message = input("\nEnter a message (or 'quit'): ")
    if message == 'quit':
        break
    print(f"You said: {message}")

# Mit continue
counter = 0
while counter < 10:
    counter += 1
    if counter % 2 == 0:  # Gerade Zahlen überspringen
        continue
    print(f"Ungerade Zahl: {counter}")

Listen mit while bearbeiten 📋

# Elemente zwischen Listen verschieben
unconfirmed_users = ['alice', 'brian', 'candace']
confirmed_users = []

while unconfirmed_users:
    current_user = unconfirmed_users.pop()
    print(f"Verifying user: {current_user.title()}")
    confirmed_users.append(current_user)

print(f"Confirmed users: {confirmed_users}")

Listen bereinigen 🧹

# Alle Vorkommen eines Wertes entfernen
pets = ['dog', 'cat', 'dog', 'goldfish', 'cat', 'rabbit', 'cat']
print(f"Vorher: {pets}")

while 'cat' in pets:
    pets.remove('cat')

print(f"Nachher: {pets}")
# Ausgabe: ['dog', 'dog', 'goldfish', 'rabbit']

Umfragen mit while-Schleifen 📝

# Dictionary mit while füllen
responses = {}
polling_active = True

while polling_active:
    name = input("\nWhat is your name? ")
    response = input("Which mountain would you like to climb? ")
    responses[name] = response
    
    repeat = input("Would you like to let another person respond? (yes/no) ")
    if repeat == 'no':
        polling_active = False

# Ergebnisse anzeigen
print("\n--- Poll Results ---")
for name, mountain in responses.items():
    print(f"{name} would like to climb {mountain}.")

Häufige Fehler 🚫➡️✅

Best Practices ✅

Next: Kapitel 9 - Funktionen 🎯

Was erwartet uns?

• Funktionen definieren: Code in wiederverwendbare Blöcke packen
• Parameter & Argumente: Daten an Funktionen übergeben
• Rückgabewerte: Ergebnisse zurückgeben
• *args & **kwargs: Flexible Argumentenzahl
• Module: Code organisieren und teilen

def greet_user(name, greeting="Hello"):
    """Greet a user with a personalized message."""
    return f"{greeting}, {name}!"

message = greet_user("Alice", "Hi")
print(message)  # "Hi, Alice!"

Zusammenfassung 🎓

🚀 Bereit für Funktionen? Let's go! 🚀