Interactive use of R is achieved through the command-line interface
(CLI) provided by the
component—this is where users issue commands for R to parse and then
evaluate. RStudio provides a console that behaves pretty much like any other
console R users have seen, such as the one provided by the RGui for Windows.
This chapter describes command-line usage in RStudio, along with some of the
components providing direct support for interactive usage.
The simplest use of R involves typing one or more commands at the
prompt (usually a
> symbol) and then pressing the enter key.
Commands can be combined on one line if separated by a semicolon and can
extend over multiple lines. Once entered, the command is sent back to the
R interpreter. If the commands are complete and there are no errors, R
returns the output from the call. Usually, this output is displayed in the
Console. The first command in Figure 3-1 shows how RStudio responds to the command to
add 2 and 2. To distinguish parts of the text, the commands appear in one
color and the output in another (by default). Some calls (e.g.,
assignment, graphic commands, function calls returned by
invisible) return no printed output. In the
RStudio console, the input and output may be perused by the user and
copy-and-pasted, but may not be directly edited. (The
History pane is used instead.)
When a command is not complete, R’s parser will recognize this and allow the user to type ...