A purrr tutorial

This repo hosts the materials for a purrr tutorial. The materials currently reflect the version planned for the useR! Brussels, Belgium, July 2017.

Upcoming in-person tutorials

• useR! Brussels, Belgium, July 4 2017
• London R-ladies London, U.K., July 12 2017

Older versions of the materials, from prior in-person tutorials, are also available:

• Cascadia R Conf June 3 2017 (1.75 hours)

• rstudio::conf Jan 2017 (2.25 hours)

Outline

Code with a lot of duplication is harder to understand, troubleshoot and maintain. The goal of this tutorial is help you remove duplication in your code by using functions that write for loops for you.

You'll learn to use the functions in the purrr package to perform iterative tasks: tasks that look like "for each _____ do _____".

By the end of the tutorial you'll be writing code that is more readable and easier to update and you'll be ready to solve new iteration problems faster and with fewer mistakes.

Learning Objectives

By the end of the tutorial, you'll be able to:

• Move from solving a problem on a single element, to iterating that solution over many elements with map().
• Identify when to use the typed variants of map(): map_lgl(), map_int(), walk() etc.
• Iterate over two arguments with map2().
• Leverage purrr to get list data into tibbles.
• Use purrr to work with list columns in tibbles.

Pre-requisites

Don't worry if you have never written a for loop, used lapply(), written your own function or heard of a tibble, this tutorial is designed to be accessible to beginners.

That said, you should be familiar with exploring and subsetting the basic data structures in R including lists and data frames.

This is a hands-on tutorial, you'll need your laptop with R installed, as well as a few packages:

install.packages("tidyverse")

# install.packages("devtools")
devtools::install_github("jennybc/repurrrsive")

License

This purrr tutorial by Charlotte Wickham is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.