ggplot2 increase space between legend keys

Question

How can I increase the space between the keys of the legend of ggplot2 plot?

library(ggplot2)
ggplot(aes(mpg, wt, colour = factor(cyl)),
                


        

Answer 1

Here a solution using gtable. Basically I am extracting legend grobs table and I add a row in the legend table.

library(gtable)
library(grid)
## transform the ggplot to a grobs table
p_table <- ggplot_gtable(ggplot_build(p))
## extract legend
leg <- which(sapply(p_table$grobs, function(x) x$name) == "guide-box")
## this is the tricky part !
## add  a row in the second position (pos=2)
p_table$grobs[[leg]]$grobs[[1]] <- 
  gtable_add_rows(p_table$grobs[[leg]]$grobs[[1]], 
                  unit(0.5, "line"), ## you can increase the height here
                  pos=2)             ## since I have 2 rows , I insert it in the middle
plot(p_table)  

PS: I dont' know here how to coerce the table to a plot again! maybe someone else can help here ( I am just plotting it and losing the object structure)