R: Low-level Options Controlling Behaviour of Lattice

C_04_lattice.options {lattice} | R Documentation

## 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

`name` | character giving the name of a setting
`...` | new options can be defined, or existing ones modified, using one or more arguments of the form `name = value` or by passing a list of such tagged values. Existing values can be retrieved by supplying the names (as character strings) of the components as unnamed 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`, `aspect`, `between`, `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`).

`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)

[Package lattice version 0.20-29 Index]