Smaller gap between two legends in one plot (e.g. color and size scale)

Question

how do I reduce the gap between two guides in one plot. In the example below, the two guides are from a color and size scale and I want to change the gap between the two so

Answer 1

Now it seems to be possible using the theme parameters:

ggplot(df,aes(x=x,y=y,color=color,size=size)) + geom_point() + 
theme(legend.spacing.y = unit(-0.5, "cm"))

You can also try to decrease margins of the legends:

legend.margin = margin(-0.5,0,0,0, unit="cm")

or older

legend.margin=unit(0, "cm")

Answer 2

I tried to play to customize legend or guide parameters but I can't find a solution. I hope give a solution using ggplot2 settings.

Here 2 solutions based on the gtable and grid packages.

for the gtable solution, the code is inspired from this question.

  library(gtable)
  # Data transformation
  data <- ggplot_build(p)
  gtable <- ggplot_gtable(data)
  # Determining index of legends table
  lbox <- which(sapply(gtable$grobs, paste) == "gtable[guide-box]")
  # changing the space between the 2 legends: here -0.5 lines
  guide <- gtable$grobs[[lbox]]
  gtable$grobs[[lbox]]$heights <- unit.c(guide$heights[1:2],
                                    unit(-.5,'lines'),  ## you can the GAP here
                                    guide$heights[4:5])
  # Plotting
  grid.draw(gtable)

Similar using the grid package ( we redraw in the viewport of the legend)

pp <- grid.get('guide',grep=T)
 depth <- downViewport(pp$wrapvp$name)
 guide <- grid.get('guide',grep=T)
 grid.rect(gp=gpar(fill='white'))
 guide$heights <- unit.c(guide$heights[1:2],unit(-0.2,'lines'),guide$heights[4],unit(0.1,'lines'))
 grid.draw(guide)
 upViewport(depth)