New ways to change the text color of strip text in facet_wrap (ggplot2)?

February 26, 2024

This question has been asked and answered a few times – most recently here – but are a few years old, involve a for-loop and grid, and are a bit hacky. I was wondering if there were any new ways to change the color of my strip text to match the title text, preferably within ggplot.

library(ggplot2)
library(ggtext)

facet_colors <- c("#43A047","#8A2BE2", "#007ACC")

iris |>
  pivot_longer(-Species) |>
  ggplot(aes(x = name,
             y = value, 
             # group = Species,
             fill = Species)) +
  geom_boxplot() +
  scale_fill_manual(values = facet_colors) +
  labs(title ="Feature Comparison of <span style = 'color: #43A047;'>Setosa</span>, 
       <span style = 'color: #8A2BE2;'>Versicolor</span> and 
       <span style = 'color: #007ACC;'>Virginica</span>") +
  facet_wrap(~Species) +
  theme_minimal() +
  theme(plot.title = element_markdown())

>Solution :

As you are already using ggtext, basically the same approach applies to the strip text, e.g. using a labeller() function and setting strip.text=element_markdown() too you could do:

library(ggplot2)
library(ggtext)

facet_colors <- c("#43A047", "#8A2BE2", "#007ACC")

iris |>
  tidyr::pivot_longer(-Species) |>
  ggplot(aes(
    x = name,
    y = value,
    fill = Species
  )) +
  geom_boxplot() +
  scale_fill_manual(values = facet_colors) +
  labs(title = "Feature Comparison of <span style = 'color: #43A047;'>Setosa</span>,
       <span style = 'color: #8A2BE2;'>Versicolor</span> and
       <span style = 'color: #007ACC;'>Virginica</span>") +
  facet_wrap(~Species,
    labeller = labeller(
      Species = c(
        virginica = "<span style = 'color: #007ACC;'>Virginica</span>",
        versicolor = "<span style = 'color: #8A2BE2;'>Versicolor</span>",
        setosa = "<span style = 'color: #43A047;'>Setosa</span>"
      )
    )
  ) +
  theme_minimal() +
  theme(
    plot.title = element_markdown(),
    strip.text = element_markdown()
  )