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Lambda Functions (Anonymous Functions)

Python Programming: The 0 to Hero Bootcamp

Lambda Functions

A lambda function is a small, anonymous (has no name) inline function defined with the lambda keyword. They are restricted to a single expression, the result of which is implicitly returned.

Syntax

lambda arguments: expression

Example 1: Simple Addition

python

Standard function

def add(a, b): return a + b

Equivalent Lambda function

add_lambda = lambda a, b: a + b

print(add_lambda(5, 3)) # Output: 8

Example 2: Lambdas as Function Arguments

The primary use of lambda functions is when you need a simple, disposable function as an argument to a higher-order function (like sorted(), map(), or filter()).

Sorting based on a specific key

We want to sort a list of tuples by the second element (index 1).

python students = [('Alice', 88), ('Bob', 95), ('Charlie', 79)]

Sort by score (the second element of the tuple)

The lambda function tells sorted() which value to use for comparison

sorted_students = sorted(students, key=lambda student: student[1])

print(sorted_students)

Output: [('Charlie', 79), ('Alice', 88), ('Bob', 95)]