Question

I would like to create R plots within four regions with a layout specified by grid. Furthermore, gridBase should be used to actually plot in the regions using base graphics. Below is an example. The problem is that the 4 plots are not plotted in the four different regions, they are rather overlaid.

require(grid)
require(gridBase)

## set up the grid layout
gl <- grid.layout(2, 2, widths=unit(c(3, 3), "inches"),
          heights=unit(c(3, 3), "inches"))
pushViewport(viewport(layout=gl)) # use this layout in a viewport

## plot
par. <- par(no.readonly=TRUE) # save plot settings
vps <- baseViewports() # create list of grid viewports corresponding to inner, figure, and plot regions
pushViewport(vps$inner, vps$figure, vps$plot)
for(i in 1:2) { # rows
    for(j in 1:2) { # columns
        pushViewport(viewport(layout.pos.row=i, layout.pos.col=j))
        par(plt=gridPLT(), new=TRUE)
        x <- 1:10
        plot(x, x+runif(10), type="b")
        upViewport()
    }
}
par(par.) # reset plot settings

Answer 1

This seems to work:

require(grid)
require(gridBase)

gl <- grid.layout(2, 2, widths=unit(c(3, 3), "inches"),
          heights=unit(c(3, 3), "inches"))
pushViewport(viewport(layout=gl))

par. <- par(no.readonly=TRUE)
for(i in 1:2) {
    for(j in 1:2) {
        pushViewport(viewport(layout.pos.row=i, layout.pos.col=j))
        par(plt=gridPLT())
        x <- 1:10
        plot(x, x+runif(10), type="b", xlab="", ylab="")
        par(new=TRUE) # to be run after first plot
        upViewport()
    }
}
par(par.)