khroma and colorblindr: Tools for colorblind-friendly plots

visualization
colors
Author

Aaron Braver

Published

July 4, 2023

Load packages

khroma - colorblind-friendly palettes

khroma contains a number of color schemes that are colorblind-friendly, divided into diverging, qualitative, and sequential types:

khroma::info() |>
  group_by(type) |>
  summarize(palettes = paste(palette, collapse = ", "))
type palettes
diverging broc, cork, vik, lisbon, tofino, berlin, roma, bam, vanimo, oleron, bukavu, fes, sunset, BuRd, PRGn
qualitative bright, highcontrast, vibrant, muted, mediumcontrast, pale, dark, light, okabeito, okabeitoblack, stratigraphy, soil, land
sequential devon, lajolla, bamako, davos, bilbao, nuuk, oslo, grayC, hawaii, lapaz, tokyo, buda, acton, turku, imola, batlow, batlowW, batlowK, brocO, corkO, vikO, romaO, bamO, YlOrBr, iridescent, discreterainbow, smoothrainbow

The color function takes a palette name and returns a function, which in turn returns a palette of specified size:

library(khroma)

bright_fun <- color("bright")
bright_fun(5)
     blue       red     green    yellow      cyan 
"#4477AA" "#EE6677" "#228833" "#CCBB44" "#66CCEE" 
attr(,"missing")
[1] NA

And you can preview these palettes with plot_scheme():

plot_scheme(bright_fun(7), names = TRUE,
            colours = TRUE) # NB: `colours` must be spelled British-ly

Further, you can preview the palette as viewed by several types of colorblindness:

plot_scheme_colorblind(bright_fun(7))


Each of the schemes have built-in ggplot scales in the form scale_color_{palettename} and scale_fill_{palettename}:

plot <- midwest |> 
  filter(percbelowpoverty < 30) |> 
  ggplot(aes(x = percollege, y = percbelowpoverty, color = state)) +
    geom_point(size = 3, alpha =.5) +
    scale_color_bright()

plot
Percent of population with a college degree vs. percent of population below the poverty line, by state. Data from ggplot2::midwest

Percent of population with a college degree vs. percent of population below the poverty line, by state. Data from `ggplot2::midwest`

(NB: you can use the sequential and diverging type palettes for discrete/categorical data if you add the argument discrete = TRUE)

colorblindr - Preview your plots with colorblind simulation

colorblindr::cvd_grid will simulate how your plots will look to people with various types of colorblindness:

# remotes::install_github("clauswilke/colorblindr")

plot <- msleep |> 
  filter(!is.na(vore)) |> 
  ggplot(aes(x = sleep_rem, fill = vore)) +
  geom_density(alpha = 0.75) +
  scale_fill_light()

plot

colorblindr::cvd_grid(plot)
Density of hours of REM sleep, for carnivores, omnivores, herbivores, and insectivores. Data from the mammal sleep dataset (ggplot::msleep).

The same plot in various simulations of colorblindness