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CHAPTER 7 TRADITIONAL TRELLIS GRAPHICS
Superposing Two or More Groups of Values on a Panel
Data Structures
More on Aspect Ratio and Scales: Prepanel Functions
More on Multipanel Conditioning
Summary of Trellis Functions and Arguments
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A Roadmap of
Trellis Graphics
Trellis Graphics provide a comprehensive set of display functions that are a
popular alternative to using the traditional S-PLUS graphics functions
described in the previous chapter. The Trellis functions are particularly
geared towards multipanel and multipage plots. This chapter describes the
Trellis system based on traditional S-PLUS graphics.
Getting Started
with Trellis
Open a Trellis Graphics device with the command trellis.device. If no
device is open, Trellis commands will open one by default, but by using this
command you ensure the open graphics device is compatible with Trellis
Graphics.
> trellis.device()
General Display
Functions
The Trellis library has a collection of general display functions that draw
different types of graphs. For example, xyplot makes x-y plots, dotplot
makes dot plots, and wireframe makes 3-D wireframe displays. The
functions are general because they have the full capability of Trellis Graphics,
including multipanel conditioning.
These functions are introduced in the the section General Display Functions
(page 210).
Common
Arguments
There is a set of common arguments that all general display functions
employ. The usage of some of these arguments varies, but each has a common
purpose across all functions. Many of the general display functions also have
arguments that are specific to the types of graphs that they draw.
The common arguments, which are listed in the section Summary of Trellis
Functions and Arguments (page 266), are discussed in many sections.
Panel Functions
Panel functions are a critical aspect of Trellis Graphics. They make it easy to
tailor displays to your data even when the displays are quite complicated ones
with many panels.
The data region of a panel on a graph resulting from a general display
function is a rectangle that just encloses the data. The sole responsibility for
drawing in a data region is given to a panel function that is an argument of
the general display function. The other arguments of the general display
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