R: Function to generate a simple key

D_simpleKey {lattice} | R Documentation

## Function to generate a simple key

### Description

Simple interface to generate a list appropriate for `draw.key`

### Usage

    simpleKey(text, points = TRUE,
              rectangles = FALSE,
              lines = FALSE,
              col, cex, alpha, font,
              fontface, fontfamily,
              lineheight, ...)

### Arguments

`text` | character or expression vector, to be used as labels for levels of the grouping variable
`points` | logical
`rectangles` | logical
`lines` | logical
`col, cex, alpha, font, fontface, fontfamily, lineheight` | Used as top-level components of the list produced, to be used for the text labels. Defaults to the values in `trellis.par.get("add.text")`
`...` | further arguments added to the list, eventually passed to `draw.key`

### Details

A lattice plot can include a legend (key) if an appropriate list is specified as the `key` argument to a high level Lattice function such as `xyplot`. This key can be very flexible, but that flexibility comes at a cost: this list needs to be fairly complicated even in simple situations. `simpleKey` is designed as a useful shortcut in the common case of a key drawn in conjunction with a grouping variable, using the default graphical settings.

The `simpleKey` function produces a suitable `key` argument using a simpler interface. The resulting list will use the `text` argument as a text component, along with at most one set each of points, rectangles, and lines. The number of entries (rows) in the key will be the length of the `text` component. The graphical parameters for the additional components will be derived from the default graphical settings (wherein lies the simplification, as otherwise these would have to be provided explicitly).

Calling `simpleKey` directly is usually unnecessary. It is most commonly invoked (during the plotting of the `"trellis"` object) when the `auto.key` argument is supplied in a high-level plot with a `groups` argument. In that case, the `text` argument of `simpleKey` defaults to `levels(groups)`, and the defaults for the other arguments depend on the relevant high-level function. Note that these defaults can be overridden by supplying `auto.key` as a list containing the replacement values.

### Value

A list that would work as the `key` argument to `xyplot`, etc.

### Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

### See Also

`Lattice`, `draw.key`, `trellis.par.get`, and `xyplot`, specifically the entry for `auto.key`.

[Package lattice version 0.20-29 Index]