Functional Programming: Filter and Reduce

Learning Objectives Define functional programming and its core idea of using pure functions. Explain the purpose of the `filter()` function for selecting data. Use `filter()` with a lambda function to create a new list based on a specific condition. Explain the purpose of the `reduce()` function for aggregating data. Use `reduce()` with a lambda function to compute a single value from a list. Combine `filter()` and `reduce()` to solve multi-step data processing problems. Differentiate between using `filter()` and a traditional `for` loop with an `if` statement. Ever wanted to pick out all the high scores from a list or find the total of your shopping cart with just one line of code? 🛒🎮 Welcome to the world of functional programming! In this lesson, you'll learn abo...

TermDefinitionExample Functional ProgrammingA style of programming where you build programs by applying and composing functions. It avoids changing data and focuses on creating predictable code by treating functions like mathematical equations.Instead of a loop that modifies a variable, you'd use functions like `filter` or `reduce` that take a list and produce a new result without changing the original list. Higher-Order FunctionA special type of function that can take another function as an argument or that returns a function as its result.`filter()` is a higher-order function because you give it another function (the condition) to do its job. filter()A built-in Python function that creates a new collection of items by 'filtering' an existing one. It keeps only the items f...

filter() Syntax list(filter(condition_function, iterable)) Use this pattern to create a new list containing only the elements from the `iterable` (like a list) that make the `condition_function` true. We wrap it in `list()` because `filter` itself doesn't return a list directly. reduce() Syntax from functools import reduce reduce(combining_function, iterable) Use this pattern to boil down an `iterable` to a single value. The `combining_function` must take two arguments: the accumulated result so far and the next item from the list. Remember to import it first! Lambda Function Pattern lambda arguments: expression This is a shortcut for creating a simple function. Use it inside `filter()` or `reduce()` to define your logic on the fly. The `expression` is what the...