Statistics: An Introduction Using R, 2nd Edition

AppendixEssentials of the R Language

R as a Calculator

The command line after the screen prompt > is an excellent calculator:

> log(42/7.3)
[1] 1.749795

By default, logs in R are base e (natural or Napierian, not base 10 logs), but you can specify any base you want, as a second argument to the logfunction. Here is log base 2 of 16:

> log(16,2)
[1] 4

Each line can have many characters, but if you want to evaluate a complicated expression, you might like to continue it on one or more further lines for clarity. The way you do this is by ending the line at a place where the line is obviously incomplete (e.g. with a trailing comma, operator, or with more left parentheses than right parentheses, implying that more right parentheses will follow). When continuation is expected, the line prompt changes from > to +

> 5+6+3+6+4+2+4+8+
+                      3+2+7
[1] 50

Note that the + continuation prompt does not carry out arithmetic plus. If you have made a mistake, and you want to get rid of the + prompt and return to the > prompt, then press the Esc key and use the Up arrow to edit the last (incomplete) line.

From here onwards (and throughout the book), the prompt character > is omitted. The material that you should type on the command line is shown in red font in this book. Just press the Return key to see the answer. The output from R is shown in dark blue Courier New font, which uses absolute rather than proportional spacing, so that columns of numbers remain neatly aligned on the page and on the screen. ...