R: Reduce axis to geom_density_ridges distance after flipping plot with coord

First we prepare some toy data that sufficiently resembles the one I am working with.

rawdata <- data.frame(Score = rnorm(1000, seq(1, 0, length.out = 10), sd = 1),
                      Group = rep(LETTERS[1:3], 10000))
stdev <- c(10.78,10.51,9.42)

Now we plot the estimated densities via geom_density_ridges. I also add a grey highlight around zero via geom_rect. I also flip the chart with coord_flip.

p <- ggplot(rawdata, aes(x = Score, y = Group))  
     scale_y_discrete()  
     geom_rect(inherit.aes = FALSE, mapping = aes(ymin = 0, ymax = Inf, xmin = -0.1 * min(stdev), xmax = 0.1 * max(stdev)), 
               fill = "grey", alpha = 0.5)  
     geom_density_ridges(aes(fill = Group), scale = 0.5, size = 1, alpha=0.5)  
     scale_color_manual(values = col)     
     scale_fill_manual(values = col)  
     labs(title="Toy Graph", y="Group", x="Value")  
     coord_flip(xlim = c(-8, 8), ylim = NULL, expand = TRUE, clip = "on")

p

And this is the solution I get, which is close to what I was expecting, despite the detail of this enormous gap between the y axis an the start of the first factor in the x axis A. I tried using expand=c(0,0) inside scale_y_discrete() following some suggestions from other posts, but it does not make the gap smaller at all. If possible I would still like to have a certain gap, although minimal. I've been also trying to flip the densities in the y axis so the gap is filled by first factor density plot but I have been unsuccessful as it does not seem as trivial as one could expect.

Sorry, I know this might be technically two different questions, "How to reduce the gap from the y axis to the first density plot?" and "How to flip the densities from y axis to reduce the gap?" But I would really be happy with the first one as I understand the second question seems to be apparently less straightforward.

Thanks in advance! Any help is appreciated.

CodePudding user response：

Flipping the densities also effectively reduces the space, so this might be all you need to do. You can achieve it with a negative scale parameter:

ggplot(rawdata, aes(x = Score, y = Group))  
  scale_y_discrete()  
  geom_rect(inherit.aes = FALSE, 
            mapping = aes(ymin = 0, ymax = Inf, 
                          xmin = -0.1 * min(stdev), 
                          xmax = 0.1 * max(stdev)), 
            fill = "grey", alpha = 0.5)  
  geom_density_ridges(aes(fill = Group), scale = -0.5, size = 1, alpha = 0.5)  
  scale_color_manual(values = col)     
  scale_fill_manual(values = col)  
  labs(title = "Toy Graph", y = "Group", x = "Value")  
  coord_flip(xlim = c(-8, 8), ylim = NULL, expand = TRUE, clip = "on")

If you want to keep the densities pointing the same way but just reduce space on the left side, simply set hard limits in your coord_flip, with no expansion:

ggplot(rawdata, aes(x = Score, y = Group))  
  geom_rect(inherit.aes = FALSE, 
            mapping = aes(ymin = 0, ymax = Inf, 
                          xmin = -0.1 * min(stdev), 
                          xmax = 0.1 * max(stdev)), 
            fill = "grey", alpha = 0.5)  
  geom_density_ridges(aes(fill = Group), scale = 0.5, size = 1, alpha = 0.5)  
  scale_color_manual(values = col)     
  scale_fill_manual(values = col)  
  scale_y_discrete()  
  labs(title = "Toy Graph", y = "Group", x = "Value")  
  coord_flip(xlim = c(-8, 8), ylim = c(0.8, 4), expand = FALSE)