How to do color overlay between errorbar and bar in a bar chart?

Question

I have a bar chart with errorbars, and I want to use the same color for both bar and errorbar. However, this would mean that I could not see the bottom part of the errorbar.

library(ggplot2)
library(tibble)

my_df <- 
  tibble::tribble(~response, ~estimate, ~lower_ci, ~upper_ci,
                  "little_bit", 0.353477, 0.255625, 0.451747,
                  "no", 0.307639, 0.250436, 0.375393,
                  "very", 0.338883, 0.301007, 0.37572310)

## compare this:
ggplot(my_df, aes(x = reorder(response, -estimate), y = estimate)) +
  geom_bar(stat = "identity", width = 0.9, fill = "#6EB3FF") +
  geom_errorbar(aes(ymin = lower_ci, ymax = upper_ci),
                width = 0.1, size = 3.5)

## with this:
ggplot(my_df, aes(x = reorder(response, -estimate), y = estimate)) +
  geom_bar(stat = "identity", width = 0.9, fill = "#6EB3FF") +
  geom_errorbar(aes(ymin = lower_ci, ymax = upper_ci),
                width = 0.1, size = 3.5, color = "#6EB3FF")

---

My visual idea is to use overlay

Is there a way to achieve such overlay using ggplot?

Answer 1

A simple alpha would do.

Note you technically have different colors. Another option would be to use color modifying packages such as shades or colorspaces. See one option with colorspaces below. shades is cool when you want to change entire palettes.

library(ggplot2)
library(tibble)

my_df <- 
  tibble::tribble(~response, ~estimate, ~lower_ci, ~upper_ci,
                  "little_bit", 0.353477, 0.255625, 0.451747,
                  "no", 0.307639, 0.250436, 0.375393,
                  "very", 0.338883, 0.301007, 0.37572310)

# super easy, just make the bars mor transparent - not quite your desired look
ggplot(my_df, aes(x = reorder(response, -estimate), y = estimate)) +
  geom_bar(stat = "identity", width = 0.9, fill = "#6EB3FF", alpha  = 0.7) +
  geom_errorbar(aes(ymin = lower_ci, ymax = upper_ci),
                width = 0.1, size = 3.5,color = "#6EB3FF")

## darkening the color, and adding some alpha for your desired effect
ggplot(my_df, aes(x = reorder(response, -estimate), y = estimate)) +
  geom_bar(stat = "identity", width = 0.9, fill = "#6EB3FF") +
  geom_errorbar(aes(ymin = lower_ci, ymax = upper_ci),
                width = 0.1, size = 3.5, 
                color = colorspace::darken("#6EB3FF"), alpha  = 0.7)