ggplot2: Plotting on a grid with fewer plots than viewports

Question

library( ggplot2 )
library( gridExtra )
p1 <- qplot( rnorm( 10 ), rnorm( 10 ) )
p2 <- qplot( rnorm( 10 ), rnorm( 10 ) )
p3 <- qplot( rnorm( 10 ), rnorm( 10 ) )
p4 <- qplot( rnorm( 10 ), rnorm( 10 ) )
p5 <- qplot( rnorm( 10 ), rnorm( 10 ) )
grid.arrange( p1, p2, p3, p4, p5, nrow=2 )

I would like to center the bottom two plots. How can do this? I can do it using split.screen but I'm unable to figure out how to do this with ggplot2. ggplot2 has cooler graphics.

Thanks in advance!

PK

Answer 1

You could use the gtable package for flexible and convenient grid layouts, or simply nest two arrangeGrobs,

ng = nullGrob()
grid.arrange(arrangeGrob(p1, p2, p3, nrow=1),
             arrangeGrob(ng, p4, p5, ng, nrow=1, widths=c(0.5, 1, 1, 0.5)),
             nrow=2)

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Edit: For the bottom plots to span the full width, you simply need to remove the dummy nullGrobs() in the above solution:

grid.arrange(arrangeGrob(p1, p2, p3, nrow=1),
             arrangeGrob(p4, p5, nrow=1),
             nrow=2)