Alter just horizontal spacing between facets (ggplot2)

30
votes

ggplot2 has the ability to change the margins between a faceted plot using the argument panel.margin in opts. This seems to change both horizontal and vertical spacing. Is there a way to change the spacing of either horizontal or vertical without changing the other?

An example with outcome and desired outcome:

mtcars[, c("cyl", "am", "gear")] <- lapply(mtcars[, c("cyl", "am", "gear")], as.factor)

p <- ggplot(mtcars, aes(mpg, wt, group = cyl)) + 
    geom_line(aes(color=cyl)) +
    geom_point(aes(shape=cyl)) + 
    facet_grid(gear ~ am) +
    theme_bw()        

p + opts(panel.margin = unit(1, "lines"))

So it currently looks like:enter image description here

How can we make it look more like:enter image description here

2
rggplot2
I would have guessed you could use the four arguments for top, right, bottom and left margin but you can't. Bummer. – Luciano Selzer
@lselzer, I thought so too, but I think that option is only for plot.margin. This feature was asked about a year ago, with the answer to its availability being "not at present". – A5C1D2H2I1M1N2O1R2T1
Since the ggplot2 0.9.2 now replaces opts with theme and you can move some things independent of another (ie panel.grid.major.y etc) I figured this may work to use: theme(panel.margin.x = unit(1, "lines")) but it does not. – Tyler Rinker
Submitted an issue requesting this: github.com/hadley/ggplot2/issues/678 – Brian Diggs

2 Answers

39
votes

As of July 9th, 2015, the panel.margin.x and panel.margin.y seem to have been implemented

p <- p + theme(panel.margin.x=unit(0.5, "lines") , panel.margin.y=unit(1,"lines"))

As of December 15, 2016, 'panel.spacing' and 'panel.spacing.x' is implemented in r 3.3.2 and ggplot2 2.2.0

p <- p + theme(panel.spacing.x=unit(0.5, "lines"),panel.spacing.y=unit(1, "lines"))
9
votes

A manual solution until this feature becomes available:

library(grid)
height <- 0.5 # Vertical spacing
aux <- 1e-5 # Auxiliary number to identify 'height' among other heights
width <- 0.1 # Desirable horizontal spacing

p <- p + theme(panel.margin = unit(height + aux, "lines"))

gtable <- ggplot_gtable(ggplot_build(p))
gtable$widths[sapply(gtable$widths, '[[', 1) == height + aux][[1]][[1]] <- width
grid.draw(gtable)

enter image description here