as.layer {latticeExtra}

Overlay panels of Trellis plots on same or different scales

Description

Allows overlaying of Trellis plots, drawn on the same scales or on different scales in each of the x and y dimensions. There are options for custom axes and graphical styles.

Usage

as.layer(x, ...)

## S3 method for class 'trellis'
as.layer(x, x.same = TRUE, y.same = TRUE,
         axes = c(if (!x.same) "x", if (!y.same) "y"), opposite = TRUE,
         outside = FALSE, theme = x$par.settings, ...)

Arguments

x

a trellis object.

x.same

retains the existing panel x scale for the new layer, rather than using the layer's native x scale.

y.same

retains the existing panel y scale.

axes

which of the axes to draw (NULL for neither). Axes might not be drawn anyway, such as if scales$draw == FALSE.

opposite

whether to draw axes on the opposite side to normal: that is, the top and/or right sides rather than bottom and/or left. May be a vector of length 2 to specify for x and y axes separately.

outside

whether to draw the axes outside the plot region. Note that space for outside axes will not be allocated automatically. May be a vector of length 2 to specify for x and y axes separately.

theme

passed to layer.

...

passed to layer: typically the style argument would be specified.

Details

Panels from the trellis object x will be drawn in the corresponding panel of another trellis object, so packet numbers match (see examples).

Axis setting are taken from the trellis object x, so most scales arguments such as draw, at, labels etc will carry over to the overlaid axes. Only the main axis settings are used (i.e. left or bottom), even when opposite = TRUE.

Currently, outside top axes will be drawn in the strip if there are strips.

Value

an updated trellis object.

Author(s)

Felix Andrews [e-mail]

See Also

doubleYScale, layer, panel.axis

Examples

b1 <- barley
b2 <- barley
b2$yield <- b2$yield + 10

## panels are matched up by packet number
dotplot(variety ~ yield | site * year, b1) +
  as.layer(dotplot(variety ~ yield | site * year, b2, col = "red"))

## which gives the same result as:
dotplot(variety ~ yield | site * year, data = b1, subscripts = TRUE) +
  layer(panel.dotplot(yield[subscripts], variety[subscripts], col = "red"),
        data = b2)


## example with all same scales (the default):
xyplot(fdeaths ~ mdeaths) +
  as.layer(xyplot(fdeaths ~ mdeaths, col = 2, subset = ldeaths > 2000))

## same x scales, different y scales:
xyplot(fdeaths ~ mdeaths) +
  as.layer(bwplot(~ mdeaths, box.ratio = 0.2), y.same = FALSE)

## same y scales, different x scales:
xyplot(fdeaths ~ mdeaths) +
  as.layer(bwplot(fdeaths ~ factor(mdeaths*0), box.ratio = 0.2), x.same = FALSE)

## as.layer() is called automatically if two plots are added:
histogram(~ ldeaths, type = "density") + densityplot(~ ldeaths, lwd = 3)

## applying one panel layer to several panels of another object
xyplot(Sepal.Length + Sepal.Width ~ Petal.Length + Petal.Width | Species,
       data = iris, scales = "free") +
   as.layer(levelplot(volcano), x.same = FALSE, y.same = FALSE, under = TRUE)