How to add a title for a grid.layout figure in ggplot2?

Question

I am using grid.layout() function to arrange a number of plots in one single figure. However, I do not know how to add a main title for the whole figure (at the mid-top of the figure)?

Does anybody know this and can help me out? Many thanks!

check this: http://stackoverflow.com/questions/10776139/r-grid-layout-title — Joonbum, May 05 '16 at 14:28
I suggest this solution: https://stackoverflow.com/a/10776757/6582929 — Afshin, Jan 03 '23 at 10:30

score 21 · Accepted Answer · answered May 05 '16 at 14:48

I personally like this solution provided by cowplot maintainers on github:

Make two plots

p1 <- ggplot(mtcars, aes(x=disp, y=mpg)) + geom_point(colour = "blue") + background_grid(minor='none')
p2 <- ggplot(mtcars, aes(x=hp, y=mpg)) + geom_point(colour = "green") + background_grid(minor='none')

Use cowplot::plot_grid to combine the plots

p <- plot_grid(p1, p2, labels=c('A', 'B'))

Make a title

title <- ggdraw() + draw_label("MPG declines with displacement and horsepower", fontface='bold')

Add title

plot_grid(title, p, ncol=1, rel_heights=c(0.1, 1)) # rel_heights values control title margins

How to add a title for a grid.layout figure in ggplot2?

1 Answers1