How to get vertical lines in legend key using ggplot2 for geom_pointrange() type graphic

Question

UPDATE: The question is moot. The vertical lines in the legend key are now default for geom_pointrange() in ggplot2.

For ggplot2 graphics that have a symbol for a point estimate and a vertical line representing a range about that estimate (95% confidence interval, Inter-quartile Range, Minimum and Maximum, etc) I cannot get the legend key to show the symbol with a vertical line. Since geom_pointrange() only has arguments for ymin and ymax, I would think the intended (default) functionality of geom_pointrange(show_guide=T) would be to have vertical lines (I say default because I understand that with coord_flip one could make horizontal lines in the plot). I also understand that having vertical lines in the legend key when the legend position is right or left will have the vertical lines "run together"...but for legends in the top or bottom having a vertical line through the symbol means that the key will match what appears in the plot.

Yet the approaches I've tried still put horizontal lines in the legend key:

## set up
library(ggplot2)
set.seed(123)
ru <- 2*runif(10) - 1
dt <- data.frame(x   = 1:10, 
                 y   = rep(5,10)+ru, 
                 ylo = rep(1,10)+ru, 
                 yhi = rep(9,10)+ru,
                 s   = rep(c("A","B"),each=5),
                 f   = rep(c("facet1", "facet2"), each=5))

Default show_guide=T for geom_pointrange yields desired plot but has horizontal lines in legend key where vertical is desired (so as to match the plot):

ggplot(data=dt)+
  geom_pointrange(aes(x     = x, 
                      y     = y, 
                      ymin  = ylo, 
                      ymax  = yhi, 
                      shape = s), 
                  size=1.1,
                  show_guide=T)+
  theme(legend.position="bottom")

An attempt with geom_point and geom_segment together yields desired plot but has horizontal lines in legend key where vertical is desired (so as to match the plot):

ggplot(data=dt)+
  geom_point(aes(    x = x, 
                     y = y, 
                 shape = s), 
             size=3,
             show_guide=T)+
  geom_segment(aes(   x = x, 
                   xend = x, 
                      y = ylo, 
                   yend = yhi), 
               show_guide=T)+
  theme(legend.position="bottom")

An attempt with geom_point and geom_vline together yields desired legend key but does not respect the ymin and ymax values in the plot:

ggplot(data=dt)+
  geom_point(aes(x=x, y=y, shape=s), show_guide=T, size=3)+
  geom_vline(aes(xintercept=x, ymin=ylo, ymax=yhi ), show_guide=T)+
  theme(legend.position="bottom")

How do I get the legend key of the 3rd graph but the plot of one of the first two?

Answer 1

My solution involves plotting a vertical line with geom_vline(show_guide=T) for an x-value that is out of the bounds of the displayed x-axis along with plotting geom_segment(show_guide=F):

ggplot(data=dt)+
  geom_point(aes(x=x, y=y, shape=s), show_guide=T, size=3)+
  geom_segment(aes(x=x, xend=x, y=ylo, yend=yhi), show_guide=F)+
  geom_vline(xintercept=-1, show_guide=T)+
  theme(legend.position="bottom")+
  coord_cartesian(xlim=c(0.5,10.5))

The solution with coord_cartesian() for a numeric x axis is fine but facet_grid(scales='free_x') can be problematic:

# problem:  coord_cartesian with numeric x and facetting with scales=free_x
ggplot(data=dt)+
  geom_point(aes(x=x, y=y, shape=s), show_guide=T, size=3)+
  geom_segment(aes(x=x, xend=x, y=ylo, yend=yhi), show_guide=F)+
  geom_vline(xintercept=-1, show_guide=T)+
  theme(legend.position="bottom")+
  coord_cartesian(xlim=c(0.5,10.5))+
  facet_grid(.~f, scales="free_x")

So in that situation, another solution that might not apply in every situation, but change x values to some meaningful character of factor and then adjust the xlim:

## hack solution: adjust xlim after change x to factor or character 
## (carefully -- double check conversion):
dt$x <- factor(dt$x)
ggplot(data=dt)+
  geom_point(aes(x=x, y=y, shape=s), show_guide=T, size=3)+
  geom_segment(aes(x=x, xend=x, y=ylo, yend=yhi), show_guide=F)+
  geom_vline(xintercept=-1, show_guide=T)+
  theme(legend.position="bottom")+
  coord_cartesian(xlim=c(0.5,5.5))+
  facet_grid(.~f, scales="free_x")

Answer 2

If you don't mind having to use grid to draw the plot, you can manipulate the guide grobs directly:

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

set.seed(123)
ru <- 2*runif(10) - 1
dt <- data.frame(x   = 1:10, 
                 y   = rep(5,10)+ru, 
                 ylo = rep(1,10)+ru, 
                 yhi = rep(9,10)+ru,
                 s   = rep(c("A","B"),each=5),
                 f   = rep(c("facet1", "facet2"), each=5))

ggplot(data=dt)+
  geom_pointrange(aes(x     = x, 
                      y     = y, 
                      ymin  = ylo, 
                      ymax  = yhi, 
                      shape = s), 
                  size=1.1,
                  show_guide=T)+
  theme(legend.position="bottom") -> gg

gb <- ggplot_build(gg)
gt <- ggplot_gtable(gb)

seg <- grep("segments", names(gt$grobs[[8]]$grobs[[1]]$grobs[[4]]$children))
gt$grobs[[8]]$grobs[[1]]$grobs[[4]]$children[[seg]]$x0 <- unit(0.5, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[4]]$children[[seg]]$x1 <- unit(0.5, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[4]]$children[[seg]]$y0 <- unit(0.1, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[4]]$children[[seg]]$y1 <- unit(0.9, "npc")

seg <- grep("segments", names(gt$grobs[[8]]$grobs[[1]]$grobs[[6]]$children))
gt$grobs[[8]]$grobs[[1]]$grobs[[6]]$children[[seg]]$x0 <- unit(0.5, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[6]]$children[[seg]]$x1 <- unit(0.5, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[6]]$children[[seg]]$y0 <- unit(0.1, "npc")
gt$grobs[[8]]$grobs[[1]]$grobs[[6]]$children[[seg]]$y1 <- unit(0.9, "npc")

grid.newpage()
grid.draw(gt)