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  3. Intermediate Functional Programming with purrr
  • 1

    Programming with purrr

    Free

    Do lambda functions, mappers, and predicates sound scary to you? Fear no more! After refreshing your purrr memory, we will dive into functional programming 101, discover anonymous functions and predicates, and see how we can use them to clean and explore data.

  • 2

    Functional programming: from theory to practice

    Ready to go deeper with functional programming and purrr? In this chapter, we'll discover the concept of functional programming, explore error handling using including safely() and possibly(), and introduce the function compact() for cleaning your code.

  • 3

    Better code with purrr

    In this chapter, we'll use purrr to write code that is clearer, cleaner, and easier to maintain. We'll learn how to write clean functions with compose() and negate(). We'll also use partial() to compose functions by "prefilling" arguments from existing functions. Lastly, we'll introduce list-columns, which are a convenient data structure that helps us write clean code using the Tidyverse.

  • 4

    Case study

    We'll wrap up everything we know about purrr in a case study. Here, we'll use purrr to analyze data that has been scraped from Twitter. We'll use clean code to organize the data and then we'll identify Twitter influencers from the 2018 RStudio conference.

Initializing

Exercise

Creating lambda functions

Do you recall the three vectors visit_a, visit_b and visit_c from the A/B test from the last exercise? They are still available in your workspace.

Remember that these vectors contain the hourly visit rate by day. Each element of these vectors corresponds to one design of the website, randomly served to the visitors. We are going to turn these vectors into a daily number of visits, but this time, we'll use a mapper.

Using a mapper allows you to write reusable code: you will potentially be asked to redo this task, so if you have an already existing mapper, you will be able to reuse this object, instead of copying and pasting the same code again and again.

Instructions

100 XP
  • Get the daily number of visits by mapping an anonymous function on visit_a.
  • Make this code more concise by using a mapper.
  • Create a reusable mapper object called to_day.
  • Call to_day on the three vectors (make three calls).