Lambda with sorted() in Python

Introduction

You use lambda with sorted() to quickly tell Python how to sort things without writing a full function.

When you want to sort a list of words by their length.

When you have a list of dictionaries and want to sort by a specific key.

When you want to sort numbers based on a custom rule, like sorting by the last digit.

When you need a quick way to sort without creating a separate function.

Syntax

Python

sorted(iterable, key=lambda item: expression)

The lambda function tells sorted() how to compare each item.

The 'key' argument is where you put the lambda to customize sorting.

Examples

Sorts numbers normally from smallest to largest.

Python

sorted([5, 2, 9, 1], key=lambda x: x)

Sorts words by their length.

Python

sorted(['apple', 'banana', 'pear'], key=lambda x: len(x))

Sorts a list of dictionaries by the 'age' key.

Python

sorted([{'name': 'Bob', 'age': 25}, {'name': 'Ann', 'age': 20}], key=lambda x: x['age'])

Sample Program

This program sorts the list of fruits by their length using a lambda function.

Python

fruits = ['apple', 'banana', 'pear', 'kiwi']
sorted_fruits = sorted(fruits, key=lambda x: len(x))
print(sorted_fruits)

Important Notes

Lambda functions are small, unnamed functions used for simple tasks.

Using lambda with sorted() is a quick way to customize sorting without extra code.

Summary

Use lambda with sorted() to sort items by any rule you want.

The lambda goes inside the 'key' argument to tell sorted() how to compare items.

This method keeps your code short and easy to read.