Spacing between the legend keys for multiple legends in ggplot2 in R

Question

I searched through internet and I couldn't find a solution for my issue.

So to make it more solid say that we have a graph with two legends like below:

library(ggplot2)

ggplot() + 
  geom_point(data = mtcars, aes(x = disp, y = mpg, color = gear), 
             pch =20, size=18) + 
  geom_line(data = mtcars, aes(x = disp, y = mpg, size = disp/mpg*100)) +
  scale_size(range = c(0,3.5)) +
  guides(size = guide_legend("", order = 1, keywidth = 2, keyheight = 1.5), 
         color = guide_legend("", order = 2, keywidth = 1, keyheight = 1 )) +
  labs(x = "disp", y = "mpg") +
  geom_text(size=2.7, color = "grey29",  vjust=-0.8) +
  theme_bw() 

# ggsave("trial.png", width = 11.5, height = 8.5)

I can change the spacing for the first legend group related with size by using size option in guides. However, for the second group which indicates color, I can't neither make the whole group closer to the graph or reduce to size between the colored circles.

I have also tried the legend options in theme such as legend.spacing.x/y and legend.key.width/height. These options only worked for the first legend group.

Is there a way to reduce the sizes between the different color keys? Changing the sizes of the keys would be also good to discover.

To make my request clearer, here is the gaps that I want to adjust:

Thanks in advance.

score 1 · Answer 1 · answered Jul 08 '19 at 22:32

I am not exactly sure what you need, but I think you want the points in the legend be smaller. In that case, override.aes() is the function you need.

_{If your question is different, please clarify further so we can help you.}

library(ggplot2)

ggplot() + 
  geom_point(data = mtcars, aes(x = disp, y = mpg, color = gear), 
             pch =20, size=18) + 
  geom_line(data = mtcars, aes(x = disp, y = mpg, size = disp/mpg*100)) +
  scale_size(range = c(0,3.5)) +
  guides(size = guide_legend("", order = 1, keywidth = 2, keyheight = 1.5), 
         color = guide_legend("", order = 2, keywidth = 1, keyheight = 1, 
                              override.aes = list(size=9))) +
  labs(x = "disp", y = "mpg") +
  geom_text(size=2.7, color = "grey29",  vjust=-0.8) +
  theme_bw()

^{Created on 2019-07-08 by the reprex package (v0.3.0)}

Thanks, this made the legend key a bit better good-looking. However, I was trying to get legend key boxes (in these plots, they should be transparent but they are there anyways) closer to the actual plot border (frame) and/or also reduce the gaps between the colored circles in the second legend. I'm going to put another plot in the post with marking the places I wish to change in a minute. — DSA, Jul 09 '19 at 11:10

score 1 · Answer 2 · answered Jul 19 '19 at 09:55

Legend spacing is always kind of an issue and gets many votes e.g. here. I think one of the issues in your particular example could be the continuous nature of gear. Factorising might help (if you have more values than gear, use cut() instead) and then change the legend spacing within your guides call using unit(). I have boiled down your code a bit and also replace title = '' with title = NULL, as otherwise ggplot is actually drawing an empty object.

library(tidyverse)

mtcars_f <- mtcars %>% mutate(gear_f = factor(gear)) #factorising gear

ggplot(mtcars_f, aes(disp, mpg)) + 
  geom_point(aes(color = gear_f), size = 10) + 
  geom_line(aes(size = disp/mpg*100)) +
  guides(size = guide_legend(title = NULL, order = 1, 
         keyheight = unit(0.1, 'inch')), 
         color = guide_legend(title = NULL, order = 2, 
         keyheight = unit(0.1, 'inch'))) +
  scale_color_brewer(palette = 'Blues') +
  theme(legend.key= element_blank())

^{Created on 2019-07-19 by the reprex package (v0.3.0)}

Spacing between the legend keys for multiple legends in ggplot2 in R

2 Answers2