Python Lambda Functions

A Lambda Function is a small anonymous function that can have any number of arguments but only one expression.

Lambda functions are useful when you need a simple function for a short period of time.

Lambda Function Syntax

Syntax

lambda arguments : expression

Example

x = lambda a: a + 10

print(x(5))

Output:

15

Lambda Function with Multiple Arguments

Example

x = lambda a, b: a * b

print(x(5, 4))

Output:

20

Lambda Function with Three Arguments

Example

x = lambda a, b, c: a + b + c

print(x(10, 20, 30))

Output:

60

Using Lambda Inside a Function

Example

def multiplier(n):
    return lambda a: a * n

double = multiplier(2)

print(double(10))

Output:

20

Lambda with map()

The map() function applies a function to each item in an iterable.

Example

numbers = [1, 2, 3, 4]

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

print(result)

Output:

[2, 4, 6, 8]

Lambda with filter()

The filter() function filters elements based on a condition.

Example

numbers = [1, 2, 3, 4, 5, 6]

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

print(result)

Output:

[2, 4, 6]

Lambda with sorted()

Example

students = [
    {"name": "John", "age": 22},
    {"name": "Alice", "age": 20},
    {"name": "Bob", "age": 25}
]

result = sorted(students, key=lambda x: x["age"])

print(result)

Output:

[{'name': 'Alice', 'age': 20}, {'name': 'John', 'age': 22}, {'name': 'Bob', 'age': 25}]

Why Use Lambda Functions?

• Creates short and simple functions.
• Useful for one-time operations.
• Commonly used with map(), filter(), and sorted().
• Reduces the need for creating separate functions.

Summary

• Lambda functions are anonymous functions.
• They are created using the lambda keyword.
• They can accept multiple arguments.
• They can contain only one expression.
• Lambda functions are often used with map(), filter(), and sorted().
• They help write concise and readable code.