Python 24-Day Course - Day 9: Advanced Functions (*args, **kwargs, lambda)

Day 9: Advanced Functions

*args (Variable Positional Arguments)

def total(*args):
    return sum(args)

print(total(1, 2, 3))       # 6
print(total(10, 20, 30, 40)) # 100

**kwargs (Variable Keyword Arguments)

def build_profile(**kwargs):
    return {k: v for k, v in kwargs.items()}

profile = build_profile(name="Alice", age=25, city="Seoul")
print(profile)  # {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

Argument Order Rules

def func(pos, *args, key="default", **kwargs):
    print(f"pos={pos}, args={args}, key={key}, kwargs={kwargs}")

func(1, 2, 3, key="custom", extra="value")
# pos=1, args=(2, 3), key=custom, kwargs={'extra': 'value'}

Lambda Functions

Anonymous one-line functions.

square = lambda x: x ** 2
add = lambda a, b: a + b

print(square(5))   # 25
print(add(3, 4))   # 7

Higher-Order Functions: map, filter, sorted

numbers = [1, 2, 3, 4, 5]

doubled = list(map(lambda x: x * 2, numbers))
print(doubled)  # [2, 4, 6, 8, 10]

evens = list(filter(lambda x: x % 2 == 0, numbers))
print(evens)  # [2, 4]

students = [("Alice", 85), ("Bob", 92), ("Charlie", 78)]
ranked = sorted(students, key=lambda s: s[1], reverse=True)
print(ranked)  # [('Bob', 92), ('Alice', 85), ('Charlie', 78)]

Today’s Exercises

1. Create a function using *args that takes multiple lists and merges them into one.
2. Use map and lambda to create a list of word lengths from a list of strings.
3. Use filter to extract items from a list of dictionaries that meet a specific condition.