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

baptiste · Accepted Answer · 2013-05-28T17:55:14.020

12

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)

enter image description here

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)

enter image description here

edited May 28 '13 at 17:55

answered May 28 '13 at 16:24

baptiste

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Loved the answer but would be interested in seeing the `gtable` answer you discussed as well. +1 – Tyler Rinker May 28 '13 at 17:35
Thanks. What would be better was if the bottom plots filled the space. – polarise May 28 '13 at 17:50

baptiste · Answer 2 · 2013-08-03T15:30:36.937

Here's an alternative way using gtable:

library(gtable)
gtable_add_grobs <- gtable_add_grob #misleading name

g <- gtable(widths = unit(rep(1, 6), "null"), # need lcm(3,2)=6 for the matrix rows
            heights = unit(rep(1, 2), "null"))

#gtable_show_layout(g)

g <- gtable_add_grobs(g, lapply(list(p1, p2, p3, p4, p5), ggplotGrob),
                     t = c(1, 1, 1, 2, 2),
                     l = c(1, 3, 5, 2, 4),
                     r = c(2, 4, 6, 3, 5))

grid.newpage()
grid.draw(g)

Edit: For the bottom plots to span the full width, you simply need to alter the corresponding l and r indices,

g <- gtable_add_grobs(g, lapply(list(p1, p2, p3, p4, p5), ggplotGrob),
                      t = c(1, 1, 1, 2, 2),
                      l = c(1, 3, 5, 1, 4),
                      r = c(2, 4, 6, 3, 6))

ggplot2: Plotting on a grid with fewer plots than viewports

2 Answers2