Dashed Line for facet_grid in ggplot2

Question

I want to create a dashed line between facet grid ggplot2 plot.

data_people <- data.frame(Group = c("Good", "Medium", "Medium", "Medium", "Medium",  "BAD", "BAD", "BAD", "BAD"),
                          people = c("Jonney", "Eva", "Eilse", "Doe", "Matt", "June", "Som", "Clara","Nick"),
                          number = c(0.04, 0.09, 0.10, 0.13, 0.13, 0.06, 0.05, 0.00, 0.3))

library(ggplot2)
library(ggstance)

ggplot(data = data_people, aes(x = number, y = people, group = Group)) +
  geom_barh(stat = "identity", colour = "black") + 
  scale_x_continuous(breaks = c(-0.20, 0.00, 0.20, 0.40, 0.60, 0.80, 1.00),
                     limits = c(-0.20, 1)) +
  facet_grid(Group~., scales = "free_y", space = "free_y", switch = 'y') +
  xlab(" ") +
  ylab(" ")

What I get is this Figure.

What I want to get is this Figure.

score 3 · Answer 1 · answered Jul 02 '21 at 12:49

There's no way to do this directly with ggplot, instead it's necessary to alter the grob and redraw. Adapting the excellent answer here you can do:

library(ggplot2)
library(grid)
library(gtable)

p <- ggplot(data = data_people, aes(x= number, y = people, group = Group)) +
  geom_bar(stat = "identity", colour = "black") +
  scale_x_continuous(breaks = c(-0.20, 0.00, 0.20, 0.40, 0.60, 0.80, 1.00), limits = c(-0.20, 1)) +
  facet_grid(Group ~ ., scales = "free_y", space = "free_y", switch = 'y') + xlab(" ") +
  ylab(" ") +
  theme()

gt <- ggplotGrob(p)

panels <- subset(gt$layout, grepl("panel", gt$layout$name), t:r)

rows <- unique(panels$b)[-length(unique(panels$b))] + 1

g <- linesGrob(x = unit(c(0, 1), "npc"),
              y = unit(c(.5, .5), "npc"),
              gp = gpar(col = "black", lty = "dotted", lwd = 5) )

gt <- gtable_add_grob(gt, 
                      rep(list(g), length(rows)),
                      r = min(panels$r) - 1, t = rows, l = max(panels$l))

grid.newpage()
grid.draw(gt)

Edo · Answer 2 · 2021-07-02T12:47:20.310

This is the closest I've got so far.

With panel.spacing you adjust the distance between graphs and with panel.border you can define the line around the graphs. If you remove linetype = "dashed" you get just a simple separation line which I think looks better, but it's your call.

library(ggplot2)
# library(ggstance) ## unnecessary

ggplot(data = data_people, aes(x = number, y = people)) +
  geom_col(colour = "black") + 
  scale_x_continuous(n.breaks = 7, limits = c(-0.20, 1)) +
  facet_grid("Group", scales = "free_y", space = "free_y", switch = 'y') +
  labs(x = "", y = "") +
  theme(panel.spacing = unit(0, "lines"),
        panel.border = element_rect(fill = NA, color = "black", linetype = "dashed"))

Dashed Line for facet_grid in ggplot2

2 Answers2