strip.default: Default Trellis Strip Function

Description

strip.default is the function that draws the strips by default in 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),
              strip.levels = c(TRUE, FALSE),
              sep = " : ",
              style = 1,
              horizontal = TRUE,
              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 specifying the current levels of each of the conditioning variables (thus, this would be unique for each distinct packet). This is identical to the

var.name

vector of character strings or expressions as long as the number of conditioning variables. The contents are interpreted as names for the conditioning variables. Whether they are shown on the strip depends on the values of strip.names<

factor.levels

vector of character strings or expressions giving the levels of the conditioning variable currently being drawn. For more than one conditioning variable, this will vary with which.given. Whether these levels are shown on the str

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.

strip.levels

a logical vector of length 2, indicating whether or not the level 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.

sep

character or expression, serving as a separator if the name and level are both to be shown.

style

integer, with values 1, 2, 3, 4 and 5 currently supported, controlling how the current level of a factor is encoded. Ignored for shingles (actually, when shingle.intervals is non-null.

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horizontal

logical, specifying whether the labels etc should be horizontal. horizontal=FALSE is useful for strips on the left of panels using strip.left=TRUE

par.strip.text

list with parameters controlling the text on each strip, with components col, cex, font, etc.

strip background color.

strip foreground color.

...

arguments to be passed on to strip.default, overriding whatever value it would have normally assumed

Value

strip.default is called for its side-effect, which is to draw a strip appropriate for multi-panel Trellis conditioning plots. strip.custom returns a function that is similar to strip.default, but with different defaults for the arguments specified in the call.

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. Traditional use is as strip = function(...) strip.default(style=2,...), though this can be simplified by the use of strip.custom.

Examples

Run this code

## Traditional use
xyplot(Petal.Length ~ Petal.Width | Species, iris,
       strip = function(..., style) strip.default(..., style = 4))

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

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