Graphical procedures

 Graphical facilities are an important and extremely versatile component of the . environment. It is possible to use the facilities to display a wide variety of statistical graphs and also to build entirely new types of graph.

The graphics facilities can be used in both interactive modes, but in most cases, interactive use is more productive. Interactive use is also easy because at startup time . initiates a graphics device driver which opens a special graphics window for the display of interactive graphics. Although this is done automatically, it is useful to know that the command used is X11() under UNIX, Windows() under Windows 95 and Windows NT, and Macintosh() on a Macintosh.

Once the device driver is running, . plotting commands can be used to produce a variety of graphical displays and to create entirely new kinds of display.

Plotting commands are divided into three basic groups:

High-level

plotting functions create a new plot on the graphics device, possibly with axes, labels, titles and so on.

Low-level

plotting functions add more information to an existing plot, such as extra points, lines and labels.

Interactive

graphics functions allow you interactively add information to, or extract information from, an existing plot, using a pointing device such as a mouse.

In addition, . maintains a list of graphical parameters which can be manipulated to customise your plots.