lattice (version 0.7-1)

trellis.par.get: Graphical Parameters for Trellis Displays

Description

Functions used to query, display and modify graphical parameters for fine control of Trellis displays.

Usage

trellis.par.get(name = NULL)
trellis.par.set(name, value, warn)
show.settings(x = NULL)
lattice.theme

Arguments

name

character giving the name of a component. For a list of valid values type names(trellis.par.get()).

value

a list giving the desired value of the component.

warn

logical, whether a warning should be issued when trellis.par.get is called when no graphics device is open

x

optional list of components that change the settings (any valid value of theme in lset). These are used to modify the current settings (obtained by trellis.par.get) before they are displayed

Value

• trellis.par.get returns a list giving parameters for that component. If name is missing, it returns the full list.

Details

The various graphical parameters (color, line type, background etc) that control the look and feel of Trellis displays are highly customizable. Also, R can produce graphics on a number of devices, and it is expected that a different set of parameters would be more suited to different devices. These parameters are stored in a global variable named lattice.theme, which is a list whose components define settings for particular devices. The components are idenified by the name of the device they represent (as obtained by .Device), and are created as and when new devices are opened for the first time using trellis.device (or Lattice plots are drawn on a device for the first time in that session).

The initial settings for each device defaults to values appropriate for that device. In practice, this boils down to three distinct settings, one for screen devices like x11 and windows, one for black and white plots (mostly useful for postscript) and one for color printers (color postcript, pdf).

Once a device is open, it's settings can be modified. When another instance of the same device is opened later using trellis.device, the settings for that device are reset to its defaults, unless otherwise specified in the call to trellis.device. But settings for different devices are treated separately, i.e., opening a postscript device will not alter the x11 settings, which will remain in effect whenever an x11 device is active.

The functions trellis.par.* are meant to be interfaces to the global settings. They always apply on the settings for the currently ACTIVE device.

trellis.par.get, called without any arguments, returns the full list of settings for the active device. With the name argument present, it returns that component only. trellis.par.get sets the value of the name component of the current active device settings to value.

trellis.par.get is usually used inside trellis functions to get graphical parameters before plotting. Modifications by users via trellis.par.set is typically done as follows:

add.line <- trellis.par.get("add.line")

add.line$col <- "red"

trellis.par.set("add.line", add.line)

The actual list of the components in trellis.settings has not been finalized, so I'm not attempting to list them here. The current value can be obtained by print(trellis.par.get()). Most names should be self-explanatory.

show.settings provides a graphical display summarizing some of the values in the current setting.

There are a few more (non S compatible) interface functions which might be simpler to use. Details can be found in the documentation for lset.

See Also

trellis.device, lset, trellis.par.get,Lattice

Examples

show.settings()