R in a Nutshell, 2nd Edition

The R Console

The R console is the most important tool for using R. The R console is a tool that allows you to type commands into R and see how the R system responds. The commands that you type into the console are called expressions. A part of the R system called the interpreter will read the expressions and respond with a result or an error message. Sometimes, you can also enter an expression into R through the menus.

If you’ve used a command line before (for example, the cmd.exe program on Windows) or a language with an interactive interpreter such as LISP, this should look familiar.^[4] If not, don’t worry. Command-line interfaces aren’t as scary as they look. R provides a few tools to save you extra typing, to help you find the tools you’re looking for, and to spot common mistakes. Besides, you have a whole reference book on R that will help you figure out how to do what you want.

Personally, I think a command-line interface is the best way to analyze data. After I finish working on a problem, I want a record of every step that I took. (I want to know how I loaded the data, if I took a random sample, how I took the sample, whether I created any new variables, what parameters I used in my models, etc.) A command-line interface makes it very easy to keep a record of everything I do and then re-create it later if I need to.

When you launch R, you will see a window with the R console. Inside the console, you will see a message like this:

R version 2.15.1 (2012-06-22) -- "Roasted Marshmallows" ...