Python Lambda Functions: Beginner-Friendly Overview

Explanation:

A lambda function in Python is a small anonymous function defined using the lambda keyword. It can take any number of arguments but can only have one expression. The expression is evaluated and returned.

Syntax:

lambda arguments: expression

Example:

# A lambda function that adds 10 to the input
add_ten = lambda x: x + 10
print(add_ten(5))  # Output: 15

Use Cases:

• Short functions that are used once or a few times.

• Used with higher-order functions like map(), filter(), and reduce().

Common Tricks:

• Simplifying small functions:

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

 # Can be simplified as:
add = lambda a, b: a + b

• Using with map():

numbers = [1, 2, 3, 4, 5]
squares = list(map(lambda x: x**2, numbers))
# squares will be [1, 4, 9, 16, 25]

• Using with filter():

numbers = [1, 2, 3, 4, 5]
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
# even_numbers will be [2, 4]

• Using with reduce() from functools:

from functools import reduce
numbers = [1, 2, 3, 4, 5]
product = reduce(lambda x, y: x * y, numbers)
# product will be 120