lattice (version 0.9-13)

print.trellis: Print Trellis Objects

Description

Print (plot) a trellis object.

Usage

## S3 method for class 'trellis':
print(x, position, split,
     more = FALSE, newpage = TRUE,
     panel.height = list(1, "null"),
     panel.width = list(1, "null"),
     ...)

Arguments

x

The object to be plotted, of class ``trellis''

position

a vector of 4 numbers, typically c(xmin, ymin, xmax, ymax) that give the lower-left and upper-right corners of a rectangle in which the Trellis plot of x is to be positioned. The coordinate system for this rectangle is [0-1] in both the x and

split

a vector of 4 integers, c(x,y,nx,ny) , that says to position the current plot at the x,y position in a regular array of nx by ny plots. (Note: this has origin at top left)

more

A logical specifying whether more plots will follow on this page.

newpage

A logical specifying whether the plot should be on a new page. This option is specific to lattice, and is useful for including lattice plots in an arbitrary grid viewport (see the details section).

panel.width, panel.height

lists with 2 components, that should be valid x and units arguments to unit() (the data argument cannot be specified currently, but can be considered for addition if needed). The resulting

...

extra arguments, ignored

Details

This is the default print method for objects of class "trellis", produced by calls to functions like xyplot, bwplot etc. It is usually called automatically when a trellis object is produced. It can also be called explicitly to control plot positioning by means of the arguments split and position.

When newpage = FALSE, the current grid viewport is treated as the plotting area, making it possible to embed a Lattice plot inside an arbitrary grid viewport.

The print method uses the information in x (the object to be printed) to produce a display using the Grid graphics engine. At the heart of the plot is a grid layout, of which the entries of most interest to the user are the ones containing the display panels.

Unlike in older versions of Lattice (and Grid), the grid display tree is retained after the plot is produced, making it possible to access individual viewport locations and make additions to the plot. The full tree can be viewed using the grid function current.vpTree, and individual viewports can be `seeked' using seekViewport. The viewports that correspond to panels (which is what the user would be interested in) have names of the form panel.n, where n is a simple incremental counter for the panels. These names can be used in seekViewport. For multi-page displays, only the viewports for the last page are available. This functionality is still very new, and details may change in the future.

See Also

Lattice, unit

Examples

data(singer)
p11 <- histogram( ~ height | voice.part, data = singer, xlab="Height")
p12 <- densityplot( ~ height | voice.part, data = singer, xlab = "Height")
p2 <- histogram( ~ height, data = singer, xlab = "Height")
data(sunspot)
p3 <- xyplot(sunspot~1:37, aspect="xy", type = "l")
## simple positioning by split
print(p11, split=c(1,1,1,2), more=TRUE)
print(p2, split=c(1,2,1,2))

## Combining split and position:
print(p11, position = c(0,0,.75,.75), split=c(1,1,1,2), more=TRUE)
print(p12, position = c(0,0,.75,.75), split=c(1,2,1,2), more=TRUE)
print(p3, position = c(.5,.75,1,1), more=FALSE)

## Using seekViewport
data(longley)

## repeat same plot, with different polynomial fits in each panel
xyplot(Armed.Forces ~ Year, longley, index.cond = list(rep(1, 6)),
       panel = function(x, y, panel.counter, ...)
       {
           panel.xyplot(x, y, ...)
           fm <- lm(y ~ poly(x, panel.counter))
           llines(x, predict(fm))
       })

grid::seekViewport("panel.1")
cat("Click somewhere inside the first panel:\n")
ltext(grid::grid.locator(), lab = "linear")

grid::seekViewport("panel.1")
grid::grid.text("linear")

grid::seekViewport("panel.2")
grid::grid.text("quadratic")

grid::seekViewport("panel.3")
grid::grid.text("cubic")

grid::seekViewport("panel.4")
grid::grid.text("degree 4")

grid::seekViewport("panel.5")
grid::grid.text("degree 5")

grid::seekViewport("panel.6")
grid::grid.text("degree 6")