Adding the errorbar icon in legend in ggplot

Question

I am plotting some time series and the error bars (geom_errorbar) showing the SD of the means. I am using ggplot and I want to make the error bars visible in the legend, like this below (done in MatLab):

Error bar in legend

Is it possible?

Answer 1

thanks to the comment from @user20650 I got this solution, that works with:

t <- data.frame(x=c("A", "B"), y=c(0.5,1), ci=c(0.25, 0.25), color=c("Yes", "No"))
library(ggplot2)
library(grid)

GeomErrorbar$draw_key  <-   function (data, params, size) {
  data$linetype[is.na(data$linetype)] <- 0 ;
  segmentsGrob(c(0.2, 0.2, 0.5),
               c(0.2, 0.8, 0.2),
               c(0.8, 0.8, 0.5),
               c(0.2, 0.8, 0.8),
               gp = gpar(col = alpha(data$colour,
                                     data$alpha), 
                         lwd = data$linewidth * .pt,
                         lty = data$linetype,
                         lineend = "butt"), 
               arrow = params$arrow) }

t %>% ggplot(aes(x=x, y=y, color=color))+
  geom_point()+
  geom_errorbar(aes(ymin=y-ci, ymax=y+ci))