Colorize legend value labels to match the colors of the points of the scatter plot

Question

How do you colorize the values of the legend value labels (currently in gray) to match exactly the colors of the points of the scatter plot?

library(ggplot2)
ggplot(diamonds, aes(x=carat, y=price, col=cut)) + 
  geom_point()

Answer 1

To color the legend text labels according to the points I would suggest to use a named color vector and some styling via HTML/CSS using ggtext inside a scale_color_manual:

library(ggplot2)
library(ggtext)

pal_viridis5 <- scales::viridis_pal()(5)
names(pal_viridis5) <- levels(diamonds$cut)

ggplot(diamonds, aes(x = carat, y = price, col = cut)) +
  geom_point() +
  scale_color_manual(
    values = pal_viridis5,
    labels = ~ paste0("<span style='color: ", pal_viridis5[.x], "'>", .x, "</span>")
  ) +
  theme(legend.text = ggtext::element_markdown())