[R] Construct plot combination using grid without plotting and retrieving an object?

[Paul Murrell]

Hi

On 05/24/13 20:24, Johannes Graumann wrote:
> Hi,
>
> I'm currently combining multiple plots using something along the lines
> of the following pseudo-code:
>
> library(grid)
> grid.newpage()
> tmpLayout <- grid.layout(
>      nrow=4,
>      ncol=2)
> pushViewport(viewport(layout = tmpLayout))
>
> and than proceeding with filling the viewports ... works fine, but for
> packaging of functions I would really prefer if I could assemble all of
> this in an object which in the end would be callable with "print".
>
> I'm envisioning something along the lines of what I can do with
> ggplot2: return a plot as a ggpplot object and plot it later rather
> than as I assemble it. Is that possible with a complex grid figure?
>
> Thanks for any pointers.

You can work off-screen with grobs and gTrees and vpTrees, for example ...

library(grid)
vplay <- viewport(layout=grid.layout(2, 2),
                   name="vplay")
vp.1.1 <- viewport(layout.pos.col=1, layout.pos.row=1,
                    name="vp.1.1")
vp.2.2 <- viewport(layout.pos.col=2, layout.pos.row=2,
                    name="vp.2.2")
x <- gTree(childrenvp=vpTree(vplay, vpList(vp.1.1, vp.2.2)),
            children=gList(
                rectGrob(vp="vplay::vp.1.1", gp=gpar(fill="grey")),
                textGrob("1", vp="vplay::vp.1.1"),
                rectGrob(vp="vplay::vp.2.2", gp=gpar(fill="grey")),
                textGrob("2", vp="vplay::vp.2.2")))
grid.newpage()
grid.draw(x)

... is that the sort of thing you mean?

Paul

> Joh
>
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
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64 9 3737599 x85392
paul at stat.auckland.ac.nz
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