strip.default {lattice} | R Documentation

## In-built Trellis Strip Function

### Description

`strip.default` is the function that draws the strips by default in conditioning Trellis plots. Users can write their own strip functions, but most commonly this involves calling `strip.default` with a slightly different arguments. `strip.custom` provides a convenient way to obtain new strip functions that differ from `strip.default` only in the default values of certain arguments.

### Usage

    strip.default(which.given,
                  which.panel,
                  var.name,
                  factor.levels,
                  shingle.intervals,
                  strip.names = c(FALSE, TRUE),
                  style = 1,
                  bg = trellis.par.get("strip.background")$col[which.given],
                  fg = trellis.par.get("strip.shingle")$col[which.given],
                  par.strip.text = trellis.par.get("add.text"))
    strip.custom(...)

### Arguments

`which.given` | integer index specifying which of the conditioning variables this strip corresponds to.
`which.panel` | vector of integers as long as the number of conditioning variables. The contents are indices specifing the current levels of each of the conditioning variables (thus, this would be unique for each distinct panel).
`var.name` | vector of character strings or ecpressions as long as the number of conditioning variables. The contents are the names of the conditioning variables, to be used if the appropriate entry in `strip.names` (see below) is true.
`factor.levels` | if the current strip corresponds to a factor, this should be a character or expression vector giving the levels of the factor. Otherwise, it should be `NULL`
`shingle.intervals` | if the current strip corresponds to a shingle, this should be a 2-column matrix giving the levels of the shingle. (of the form that would be produced by printing `levels(shingle)`). Otherwise, it should be `NULL`
`strip.names` | a logical vector of length 2, indicating whether or not the name of the conditioning variable that corresponds to the strip being drawn is to be written on the strip. The two components give the values for factors and shingles respectively. This argument is ignored for a factor when `style` is not one of 1 and 3.

`style`

integer, with values 1,2,3,4,5 and 6 currently supported. Applicable only when `x` is a factor. Determines how the current level of `x` is indicated on the strip.
The best way to find out what effect the value of `style` has is to try them out. Here is a short description: for a style value of 1, the strip is colored in the background color with the strip text (as determined by other arguments) centred on it. A value of 3 is the same, except that a part of the strip is colored in the foreground color, indicating the current level of the factor. For styles 2 and 4, the part corresponding to the current level remains colored in the foreground color, however, for style = 2, the remaining part is not colored at all, whereas for 4, it is colored with the background color. For both these, the names of all the levels of the factor are placed on the strip from left to right. Styles 5 and 6 produce the same effect (they are subtly different in S, this implementation corresponds to 5), they are similar to style 1, except that the strip text is not centred, it is instead postioned according to the current level.
Note that unlike S-PLUS, the default value of `style` is 1.

`par.strip.text` | list with parameters controlling the text on each strip, with components `col`, `cex`, `font`, etc.
`bg` | strip background color.
`fg` | strip foreground color.
`...` | arguments to be passed on to `strip.default`, overriding whatever value it would have normally assumed

### Details

default strip function for trellis functions. Useful mostly because of the `style` argument — non-default styles are often more informative, especially when the names of the levels of the factor `x` are small. Typical use is as `strip = function(...) strip.default(style=2,...)`.

### Value

`strip.default` is useful for its side-effect, which is to draw a strip appropriate for conditioning Trellis plots. `strip.default` returns a function similar to `strip.default`

### Author(s)

Deepayan Sarkar Deepayan.Sarkar@R-project.org

### See Also

`xyplot`, `Lattice`

### Examples

    xyplot(Petal.Length ~ Petal.Width | Species, iris,
           strip = strip.custom(style = 4))

[Package lattice version 0.11-8 Index]