Low-level Options Controlling Behaviour of Lattice

Description

Functions to handle settings used by lattice. Their main purpose is to make code maintainance easier, and users normally should not need to use these functions. However, fine control at this level maybe useful in certain cases.

Usage

lattice.options(...)
lattice.getOption(name)

Arguments

Details

These functions are modeled on options and getOption, and behave similarly for the most part. Some of the available components are documented here, but not all. The purpose of the ones not documented are either fairly obvious, or not of interest to the end-user.

panel.error

A function, or NULL. If the former, every call to the panel function will be wrapped inside tryCatch with the specified function as an error handler. The default is to use the panel.error function. This prevents the plot from failing due to errors in a single panel, and leaving the grid operations in an unmanageable state. If set to NULL, errors in panel functions will not be caught using tryCatch.

save.object

Logical flag indicating whether a "trellis" object should be saved when plotted for subsequent retrieval and further manipulation. Defaults to TRUE.

layout.widths, layout.heights

Controls details of the default space allocation in the grid layout created in the course of plotting a "trellis" object. Each named component is a list of arguments to the grid function unit (x, units, and optionally data).

Usually not of interest to the end-user, who should instead use the similiarly named component in the graphical settings, modifiable using trellis.par.set.

drop.unused.levels

A list of two components named cond and data, both logical flags. The flags indicate whether the unused levels of factors (conditioning variables and primary variables respectively) will be dropped, which is usually relevant when a subsetting operation is performed or an 'interaction' is created. See xyplot for more details. Note that this does not control dropping of levels of the 'groups' argument.

legend.bbox

A character string, either "full" or "panel". This determines the interpretation of x and y when space="inside" in key (determining the legend; see xyplot): either the full figure region ('"full"'), or just the region that bounds the panels and strips ('"panel"').

default.args

A list giving default values for various standard arguments: as.table, auto.key, aspect, between, grid, skip, strip, xscale.components, yscale.components, and axis.

highlight.gpar

A list giving arguments to gpar used to highlight a viewport chosen using trellis.focus.

banking

The banking function. See banking.

axis.padding

List with components named "numeric" and "factor", both scalar numbers. Panel limits are extended by this amount, to provide padding for numeric and factor scales respectively. The value for numeric is multiplicative, whereas factor is additive.

skip.boundary.labels

Numeric scalar between 0 and 1. Tick marks that are too close to the limits are not drawn unless explicitly requested. The limits are contracted by this proportion, and anything outside is skipped.

interaction.sep

The separator for creating interactions with the extended formula interface (see xyplot).

optimize.grid

Logical flag, FALSE by default. Complicated grid unit calculations can be slow. Sometimes these can be optimized at the cost of potential loss of accuracy. This option controls whether such optimization should be applied.

axis.units

List determining default units for axis components. Should not be of interest to the end-user.

In addition, there is an option for the default prepanel and panel function for each high-level function; e.g., panel.xyplot and prepanel.default.xyplot for xyplot. The options for the others have similarly patterned names.

Value

lattice.getOption returns the value of a single component, whereas lattice.options always returns a list with one or more named components. When changing the values of components, the old values of the modified components are returned by lattice.options. If called without any arguments, the full list is returned.

Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

See Also

options, trellis.device, trellis.par.get, Lattice

Examples

names(lattice.options())
str(lattice.getOption("layout.widths"), max.level = 2)

## Not run: 
## change default settings for subsequent plots
lattice.options(default.args = list(as.table = TRUE,
                                    grid = TRUE,
                                    auto.key = TRUE))

## End(Not run)