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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

Lambda functions

We are still working with the results of a weeklong A/B test on a website. The three vectors containing the number of visits for each design (visit_a, visit_b and visit_c) are available in your workspace.

One of your colleagues has asked you to transfer him the results, but he wants them to be rounded to the nearest ten. To do this, you will need to call the round() function this way:

Rounding to a negative number of digits means rounding to a power of ten, so for example round(x, digits = -2) rounds to the nearest hundred

Definition taken from R documentation: see ?round

Make sure to use the right map_* for each call.

Instructions

100 XP
  • Round visit_a to the nearest ten with a mapper.
  • Create a reusable mapper object called to_ten, that rounds to the nearest ten.
  • Map to_ten to visit_b.
  • Map to_ten to visit_c.