Lambda Functions - codenoteshub.com

► Understanding Lambda Functions

Lambda functions are small, anonymous functions defined in a single line. They can have any number of parameters but only one expression. Lambda functions are useful for short, simple operations that you need temporarily.

► Real-World Analogy

Think of lambda functions like sticky notes with quick instructions:
» A full function is like a detailed instruction manual with a title and multiple steps
» A lambda function is like a quick note: “Add 5” or “Multiply by 2”
» You use sticky notes for simple, one-time reminders
» You don’t need to give them formal names
» Perfect for quick tasks you won’t reuse elsewhere

► Key Concepts

✓ Anonymous functions: No name required
✓ Single expression: Can only contain one expression
✓ Inline definition: Defined where they’re used
✓ Return implicit: Automatically returns expression result
✓ Common with map(), filter(), sort(): Often used as arguments

■ Code Examples

# Basic lambda function
add = lambda x, y: x + y
print(add(5, 3))

# Lambda vs regular function
# Regular function
def square(x):
    return x ** 2

# Lambda equivalent
square_lambda = lambda x: x ** 2
print(square_lambda(4))

# Lambda with map()
numbers = &#91;1, 2, 3, 4, 5]
squared = list(map(lambda x: x ** 2, numbers))
print(f"Squared: {squared}")

# Lambda with filter()
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
print(f"Even numbers: {even_numbers}")

# Lambda with sorted()
students = &#91;('Alice', 85), ('Bob', 92), ('Charlie', 78)]
sorted_students = sorted(students, key=lambda x: x&#91;1], reverse=True)
print(f"Sorted by grade: {sorted_students}")

# Basic lambda function

add = lambda x, y: x + y

print(add(5, 3))

# Lambda vs regular function

# Regular function

def square(x):

return x ** 2

# Lambda equivalent

square_lambda = lambda x: x ** 2

print(square_lambda(4))

# Lambda with map()

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

squared = list(map(lambda x: x ** 2, numbers))

print(f"Squared: {squared}")

# Lambda with filter()

even_numbers = list(filter(lambda x: x % 2 == 0, numbers))

print(f"Even numbers: {even_numbers}")

# Lambda with sorted()

students = [('Alice', 85), ('Bob', 92), ('Charlie', 78)]

sorted_students = sorted(students, key=lambda x: x[1], reverse=True)

print(f"Sorted by grade: {sorted_students}")