Introducing geom_terrorbar()

Create galaxy-brain-level errorbars like in THAT paper

Motivation

In July 2022, a now retracted paper appeared in a special issue of a Hindawi journal Advances in Materials Science and Engineering, that contained a bar chart with the letter T pasted above bars, presumably as a substitute for error bars.

I strongly believe that everyone should be able to quickly produce this genius graphics. That is the only purpose of ggterror, an extension to R’s ggplot2 package. Unlike the graphics in the original – and this word is doing a lot of work here – paper, however, this extension produces actual errorbars.

Installation

You can install ggterror from github using the remotes package:

# install.packages("remotes")
remotes::install_github("mivalek/ggterror")

Usage

The package contains a single function geom_terrorbar() that should be used in much the same way as ggplot2::geom_errorbar()

library(ggplot2)
library(ggterror)
library(palmerpenguins)
library(dplyr)

palmerpenguins::penguins |>
    dplyr::filter(!is.na(body_mass_g)) |>
    dplyr::group_by(species) |> 
    dplyr::summarise(
        mean = mean(body_mass_g),
        se = sd(body_mass_g) / sqrt(dplyr::n())
        ) |>
        ggplot(aes(x = species, y = mean)) +
        geom_terrorbar(aes(ymin = mean - 2 * se,
                           ymax = mean + 2 * se)) +
        geom_point() +
        theme_bw()

On top of the usual aesthetics you’d pass to ggplot2::geom_errorbar(), this function takes a few additional arguments that govern the overal look of the Ts and the connecting lines:

• connect - logical. Whether or not the Ts should be connected with a line.
• fontface - one of c("plain", "bold", "italic")
• size - size of the Ts in pt units
• line_type - type of connecting line when connect = TRUE
• line_width - width of connecting line when connect = TRUE
• line_alpha - alpha for connecting line when connect = TRUE. By default, line_alpha = 0.6 * alpha of the Ts

Reproducing the original plot is easy with geom_terrorbar():

library(ggtext)

df <- tibble::tibble(
  x = factor(1:5, labels=c("blank", "pink", "lysozyme", "hOGG1", "Endo IV")),
  y = c(3.5, .5, 3.4, 3.2, 3),
  ymax = y + .2,
  ymin = y - .2,
  size = 15
)

df |> ggplot(aes(x, y)) +
  geom_terrorbar(aes(ymax = ymax, ymin = ymin), connect = FALSE) +
  geom_bar(stat = "identity", aes(fill = x), colour="black", width = .65, lwd = .7) +
  labs(x = "", y = "Current (<em>&mu;</em>A)") +
  scale_y_continuous(limits = c(0,4.3), expand=c(0,0)) +
  theme_classic() +
  scale_fill_manual(values=c("#f3c08f", "#f9ee87", "#3eaba8", "#8fc4f1", "#cecece")) +
  theme(
    panel.background = element_rect(colour = "black", fill = NA, size = .85),
    axis.text = element_text(family="serif", size = 15),
    axis.title.y = element_markdown(family = "serif", size = 15),
    axis.ticks = element_blank()) +
  guides(fill = "none")

Hope you have fun creating some true classics!