Plot min, max, median for each x value in geom_pointrange

I think you need to do the summary outside the plot function to use geom_pointrange:

library(dplyr)
library(ggplot2)
summary_diamonds <- diamonds %>% 
    group_by(cut) %>% 
    summarise(lower = min(depth), upper = max(depth), p = median(depth))

ggplot(data = summary_diamonds, mapping = aes(x = cut, y = p)) +
    geom_pointrange(mapping = aes(ymin = lower, ymax = upper))