Control Flow

  score = 85

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
else:
    grade = "F"

print(f"Grade: {grade}")
  

  status = "pass" if score >= 60 else "fail"
  

  name = ""
if name:          # empty string is falsy
    print(name)
else:
    print("Anonymous")

items = [1, 2, 3]
if items:         # non-empty list is truthy
    print(f"{len(items)} items")
  

  fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

for i in range(5):        # 0, 1, 2, 3, 4
    print(i)

for i in range(2, 10, 2): # 2, 4, 6, 8
    print(i)
  

  for index, fruit in enumerate(fruits):
    print(f"{index}: {fruit}")

names = ["Alice", "Bob"]
ages = [25, 30]
for name, age in zip(names, ages):
    print(f"{name} is {age}")
  

  user = {"name": "Alice", "age": 30, "city": "NYC"}

for key in user:
    print(key)

for key, value in user.items():
    print(f"{key}: {value}")
  

  count = 0
while count < 5:
    print(count)
    count += 1
  

  for n in range(10):
    if n == 3:
        continue   # skip 3
    if n == 7:
        break      # stop at 7
    print(n)
else:
    print("Loop completed without break")

# while with else
num = 10
while num > 0:
    num -= 1
else:
    print("Countdown finished")
  

  squares = [x**2 for x in range(10)]
evens = [x for x in range(20) if x % 2 == 0]

matrix = [[0] * 3 for _ in range(3)]

# flatten
flat = [x for row in matrix for x in row]
  

  word_lengths = {word: len(word) for word in ["hello", "world", "python"]}
# {'hello': 5, 'world': 5, 'python': 6}

filtered = {k: v for k, v in word_lengths.items() if v > 5}
  

  unique_lengths = {len(word) for word in ["hello", "world", "hi", "python"]}
# {2, 5, 6}
  

  total = sum(x**2 for x in range(1_000_000))  # no list created
  

  def handle_command(command):
    match command.split():
        case ["quit"]:
            return "Goodbye!"
        case ["load", filename]:
            return f"Loading {filename}"
        case ["save", filename]:
            return f"Saving {filename}"
        case ["greet", name, *rest]:
            return f"Hello, {name}!"
        case _:
            return "Unknown command"

print(handle_command("greet Alice"))
print(handle_command("load data.csv"))
  

  def fizzbuzz(n):
    results = []
    for i in range(1, n + 1):
        if i % 15 == 0:
            results.append("FizzBuzz")
        elif i % 3 == 0:
            results.append("Fizz")
        elif i % 5 == 0:
            results.append("Buzz")
        else:
            results.append(str(i))
    return results

# Comprehension version
fizzbuzz = lambda n: [
    "FizzBuzz" if i % 15 == 0 else
    "Fizz" if i % 3 == 0 else
    "Buzz" if i % 5 == 0 else str(i)
    for i in range(1, n + 1)
]