| trellis.par.get {lattice} | R Documentation |
Functions used to query, display and modify graphical parameters for fine control of Trellis displays.
trellis.par.get(name = NULL) trellis.par.set(name, value, warn) show.settings(x = NULL)
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
|
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 internally in a
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 traditionally done as follows:
add.line <- trellis.par.get("add.line")
add.line$col <- "red"
trellis.par.set("add.line", add.line)
lset is a usually more convenient interface to achieve
the same end (but is not compatible with S-PLUS), the equivalent usage
being:
lset(list(add.line = list(col = "red")))
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.
trellis.par.get returns a list giving parameters for that
component. If name is missing, it returns the full list.
Deepayan Sarkar deepayan@stat.wisc.edu
There are some simpler alternatives that can be used to manipulate the
settings. Details can be found in the documentation for
lset. Other related pages: trellis.device,
trellis.par.get,Lattice
show.settings()