R: Label grid grobs

showGrob {grid}

R Documentation

Label grid grobs

Description

Produces a graphical display of (by default) the current grid scene, with labels showing the names of each grob in the scene. It is also possible to label only specific grobs in the scene.

Usage

showGrob(x = NULL,
         gPath = NULL, strict = FALSE, grep = FALSE,
         recurse = TRUE, depth = NULL,
         labelfun = grobLabel, ...)

Arguments

`x`	If `NULL`, the current grid scene is labelled. Otherwise, a grob (or gTree) to draw and then label.
`gPath`	A path identifying a subset of the current scene or grob to be labelled.
`strict`	Logical indicating whether the gPath is strict.
`grep`	Logical indicating whether the gPath is a regular expression.
`recurse`	Should the children of gTrees also be labelled?
`depth`	Only display grobs at the specified depth (may be a vector of depths).
`labelfun`	Function used to generate a label from each grob.
`...`	Arguments passed to `labelfun` to control fine details of the generated label.

Details

None of the labelling is recorded on the grid display list so the original scene can be reproduced by calling grid.refresh.

Examples

    grid.newpage()
    gt <- gTree(childrenvp=vpStack(
                  viewport(x=0, width=.5, just="left", name="vp"),
                  viewport(y=.5, height=.5, just="bottom", name="vp2")),
                children=gList(rectGrob(vp="vp::vp2", name="child")),
                name="parent")
    grid.draw(gt)
    showGrob()
    showGrob(gPath="child")
    showGrob(recurse=FALSE)
    showGrob(depth=1)
    showGrob(depth=2)
    showGrob(depth=1:2)
    showGrob(gt)
    showGrob(gt, gPath="child")
    showGrob(just="left", gp=gpar(col="red", cex=.5), rot=45)
    showGrob(labelfun=function(grob, ...) {
        x <- grobX(grob, "west")
        y <- grobY(grob, "north")
        gTree(children=gList(rectGrob(x=x, y=y,
                width=stringWidth(grob$name) + unit(2, "mm"),
                height=stringHeight(grob$name) + unit(2, "mm"),
                gp=gpar(col=NA, fill=rgb(1, 0, 0, .5)),
                just=c("left", "top")),
                textGrob(grob$name,
                         x=x + unit(1, "mm"), y=y - unit(1, "mm"),
                         just=c("left", "top"))))
    })

## Not run: 
    # Examples from higher-level packages

    library(lattice)
    # Ctrl-c after first example
    example(histogram)
    showGrob()
    showGrob(gPath="plot_01.ylab")

    library(ggplot2)
    # Ctrl-c after first example
    example(qplot)
    showGrob()
    showGrob(recurse=FALSE)
    showGrob(gPath="panel-3-3")
    showGrob(gPath="axis.title", grep=TRUE)
    showGrob(depth=2)

## End(Not run)