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.
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(...)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.
integer index specifying which of the conditioning variables this strip corresponds to.
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
return value of which.packet, which is a more accurate
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 and
style (see below). By default, the names are shown for
shingles, but not for factors.
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 strip
depends on the values of strip.levels and style (see
below). factor.levels may be specified for both factors and
shingles (despite the name), but by default they are shown only for
factors. If shown, the labels may optionally be abbreviated by
specifying suitable components in par.strip.text (see
xyplot)
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
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.
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.
character or expression, serving as a separator if the name and level are both to be shown.
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.
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) centered 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 centered, it is instead
positioned according to the current level.
Note that unlike S-PLUS, the default value of style is 1.
strip.names and strip.levels have no effect if
style is not 1 or 3.
logical, specifying whether the labels etc should
be horizontal. horizontal=FALSE is useful for strips on the
left of panels using strip.left=TRUE
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
Deepayan Sarkar Deepayan.Sarkar@R-project.org
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.
xyplot, Lattice
## 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))
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