# R: Retrieve and Update Trellis Object

update.trellis {lattice} | R Documentation

## Retrieve and Update Trellis Object

### Description

Update method for objects of class `"trellis"`, and a way to retrieve the last printed trellis object (that was saved).

### Usage

    ## S3 method for class 'trellis':
    update(object,
           panel,
           aspect,
           as.table,
           between,
           key,
           auto.key,
           legend,
           layout,
           main,
           page,
           par.strip.text,
           prepanel,
           scales,
           skip,
           strip,
           strip.left,
           sub,
           xlab,
           xlim,
           ylab,
           ylim,
           par.settings,
           index.cond,
           perm.cond,
           ...)

    ## S3 method for class 'trellis':
    t(x)

    ## S3 method for class 'trellis':
    x[i, j, ..., drop = FALSE]

    trellis.last.object(warn = TRUE, ...)

### Arguments

`object, x` | The object to be updated, of class `"trellis"`.
`i, j` | indices to be used. Names are not currently allowed.
`drop` | logical, whether dimensions with only one level are to be dropped. Currently ignored, behaves as if it were `FALSE`.
`warn` | logical, whether to warn when no plot is saved.
`panel, aspect, as.table, between, key, auto.key, legend, layout, main, page, par.strip.text, prepanel, scales, skip, strip, strip.left, sub, xlab, xlim, ylab, ylim, par.settings, index.cond, perm.cond, ...` | arguments that will be used to update `object`. See details below.

### Details

All high level lattice functions such as `xyplot` produce an object of (S3) class `"trellis"`, which is usually displayed by its `print` method. However, the object itself can be manipulated and modified to a large extent using the `update` method, and then re-displayed as needed.

Most arguments to high level functions can also be supplied to the `update` method as well, with some exceptions. Generally speaking, anything that would needs to change the data within each panel is a no-no (this includes the `formula, data, groups, subscripts` and `subset`). Everything else is technically game, though might not be implemented yet. If you find something missing that you wish to have, feel free to make a request.

Not all arguments accepted by a Lattice function are processed by `update`, but the ones listed above should work. The purpose of these arguments are described in the help page for `xyplot`. Any other argument is added to the list of arguments to be passed to the `panel` function. Because of their somewhat special nature, updates to objects produced by `cloud` and `wireframe` do not work very well yet.

The `"["` method is a convenient shortcut for updating `index.cond`. The `t` method is a convenient shortcut for updating `perm.cond` in the special (but frequent) case where there are exactly two conditioning variables, when it has the effect of switching (‘transposing’) their order.

The print method for `"trellis"` objects optionally saves the object after printing it. If this feature is enabled, `trellis.last.object` can retrieve it. Note that at most one object can be saved at a time. If `trellis.last.object` is called with arguments, these are used to update the retrieved object before returning it.

### Value

An object of class `trellis`, by default plotted by `print.trellis`. `trellis.last.object` returns `NULL` is no saved object is available.

### Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

### See Also

`trellis.object`, `Lattice`, `xyplot`

### Examples

    spots <- by(sunspots, gl(235, 12, lab = 1749:1983), mean)
    old.options <- lattice.options(save.object = TRUE)
    xyplot(spots ~ 1749:1983, xlab = "", type = "l",
           scales = list(x = list(alternating = 2)),
           main = "Average Yearly Sunspots")
    update(trellis.last.object(), aspect = "xy")
    ## Not run:
    trellis.last.object(xlab = "Year")
    ## End(Not run)
    lattice.options(old.options)

[Package lattice version 0.16-5 Index]