Lambda Functions

A Lambda Function is a small, anonymous function. Unlike regular functions defined with def, lambda functions can have only one expression.

Syntax

lambda arguments : expression

Why use Lambda?

Lambdas are best used when you need a short function for a short period of time, often as an argument to another function.

1. Using with map()

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

2. Using with filter()

filter() creates a list of elements for which a function returns True.

3. Using with reduce()

reduce() from functools applies a function cumulatively to items, reducing them to a single value.

Custom Sorting with sorted()

You can use a lambda to specify a custom sort key.

Advanced Sorting: Multiple Criteria 🎯

You can sort by multiple fields by returning a tuple from the lambda.

When NOT to Use Lambdas ⚠️

Lambdas should be simple. If you need multiple lines or complex logic, use a regular function!

Coding Challenge: Custom Sorting Engine 🏆

Create a function sort_products(products, sort_by) that sorts a list of product dictionaries by different criteria using lambdas.

Quiz

Key Takeaways

✅ Lambda functions are anonymous one-liners.
✅ Syntax: lambda args : expression.
✅ Great for map(), filter(), reduce(), and sorted().
✅ Avoid lambdas for complex logic - use regular functions instead.

What's Next?

In the final lesson of this module, we'll learn how to organize our code into Modules & Packages.

Keep coding! 🚀