colorize

Version 0.2.0

The colorize package provides some simple functions for printing text in color in markdown or Quarto documents, to be rendered as HTML or LaTeX.

This is useful when writing about the use of colors in graphs or tables, where you want to print their names in their actual color to give a direct impression of the color, like “red” shown in red, or “blue” shown in blue. This is similar to the use of direct labels in graphs, which are perceptually bound closely to what is portrayed, rather than an indirect legend, which takes more cognitive energy to see what data in referred to in the graph.

The following functions are provided:

• colorize(text, color): Print the text in a given color, as in this text in red
• colorize_bg(text, color): Print the text with a background in color, as in this text in red
• colorbox(text, color, ...): Print text with background in color, but where the text is given a contrasting color designed to be most legible, as in this text in red

In the examples above, note the difference between colorize_bg() and colorbox(): when the desired color is red, colorbox() uses a lighter color (white) so the text contrasts more with the darker background.

This is somewhat similar to what RStudio does when you enter color names or hex values in code, but colorbox() uses colorspace::contrast_ratio(textcolor, color, ...) to find the textcolor that contrasts best against the background color.

The uses of color for text in visualization is far more general than represented here. Brath (2020) is a wonderful source for inspiration!

Installation

colorize is not yet on CRAN. You can install the development version of colorize from either the GitHub repo or r-universe, as follows:

remotes::install.github("friendly/colorize")
# or:
install.packages('colorize', repos = c('https://friendly.r-universe.dev'))

The package vignette, vignette("colorbox", package = "colorize") describes the use of these functions.

Example

This example simply shows how a set of color names is rendered in HTML encoding. It doesn’t print them in their colors.

library(colorize)
# define some color names

test_colors <- c("red", "blue", "green",
                 "white", "black", "gray",
                 "pink", "yellow", "darkgreen")

sapply(test_colors, colorize)
#>                                                red 
#>             "<span style='color: red;'>red</span>" 
#>                                               blue 
#>           "<span style='color: blue;'>blue</span>" 
#>                                              green 
#>         "<span style='color: green;'>green</span>" 
#>                                              white 
#>         "<span style='color: white;'>white</span>" 
#>                                              black 
#>         "<span style='color: black;'>black</span>" 
#>                                               gray 
#>           "<span style='color: gray;'>gray</span>" 
#>                                               pink 
#>           "<span style='color: pink;'>pink</span>" 
#>                                             yellow 
#>       "<span style='color: yellow;'>yellow</span>" 
#>                                          darkgreen 
#> "<span style='color: darkgreen;'>darkgreen</span>"

Related

For a purely Quarto approach, quarto-highlight-text is a Quarto extension that allows you to highlight text in a document for various formats: HTML, LaTeX, Typst, Docx, PowerPoint, Reveal.js, and Beamer.

Citation

If you find this package useful in your work, you can cite it as:

Friendly M, Zeileis A (2025). colorize: Render Text in Color for Markdown/Quarto Documents. R package version 0.2.0, https://github.com/friendly/colorize.

References

Brath, R. (2020). Visualizing with Text. A K Peters/CRC Press. https://doi.org/10.1201/9780429290565