ABSTRACT
In chapter 5 you’ll learn about the two primary tools of control flow: choices and loops. Choices, like if statements and switch() calls, allow you to run different code depending on the input. Loops, like for and while, allow you to repeatedly run code, typically with changing options.
We’d expect that you’re already familiar with the basics of these functions so we’ll briefly cover some technical details and then introduce some useful, but lesser known, features. The condition system (messages, warnings, and errors), which you’ll learn about in Chapter 8, also provides non-local control flow.
In “Choices” we dive into the details of the if statement, and then discuss the close relatives ifelse() and switch(). “Loops” starts off by reminding you of the basic structure of the for loop in R, discusses some common pitfalls, and then talks about the related while and repeat statements.
