The Art of R Programming

Tools for Composing Function Code

If you are writing a short function that’s needed only temporarily, a quick-and-dirty way to do this is to write it on the spot, right there in your interactive terminal session. Here’s an example:

> g <- function(x) {
+    return(x+1)
+ }

This approach obviously is infeasible for longer, more complex functions. Now, let’s look at some better ways to compose R code.

Text Editors and Integrated Development Environments

You can use a text editor such as Vim, Emacs, or even Notepad, or an editor within an integrated development environment (IDE) to write your code in a file and then read it into R from the file. To do the latter, you can use R’s source() function.

For instance, suppose we have functions f() and g() in ...