Why Python Lambda Functions

1 min read

Why even use lambda function in Python if normal functions can do the same thing?

Because lambdas can make your code way more readable.

First off, here's how it works.

A normal function that takes any number and returns its double looks like this.

def double(n):
		return n * 2

With lambda, it becomes this.

lambda n: n * 2

Lambda functions are anonymous, meaning they don't have a function name.

It just takes an argument n and returns n times two.

So when do you use it?

Lambda functions are best used as a callback. Meaning functions passed as an argument to another function that you probably only need once.

def fn(callback):
    callback()

fn(lambda: print("Hello from lambda!"))

Here’s a list of user, and we want to sort them by their age.

def get_age(person):
    return person['age']

people = [{'name': 'Alice', 'age': 25}, {'name': 'Bob', 'age': 30}]
sorted_people = sorted(people, key=get_age)

To do that, we pass a function as a key to the sort function.

It works. But with lambda functions, you can do the same thing in one line.

sorted_people = sorted(people, key=lambda person: person['age'])

Once you start using them, you'll wonder how you ever lived without them.