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I am trying to color a specific label on the y-axis by using: theme(axis.text.y = element_markdown(color = ...)) and it works perfectly fine. However, when I also want to prevent myself from potential label overlapping on this very same axis by using : scale_y_discrete(guide = guide_axis(check.overlap = T)) , then, the coulored label is changed. Here is a small example showing this issue.

As anyone already faced this issue? Do you have a solution for it ? Or another way of doing it?

library(ggplot2)
library(ggtext)

N              = 10
df             = data.frame(parameters = paste("paramters", seq(N), sep = "_"),
                            color      = rep("black", N))
df$parameters  = factor(df$parameters, levels = df$parameters, ordered = T)
best           = 5
df$color[best] = "red"
df
#>      parameters color
#> 1   paramters_1 black
#> 2   paramters_2 black
#> 3   paramters_3 black
#> 4   paramters_4 black
#> 5   paramters_5   red
#> 6   paramters_6 black
#> 7   paramters_7 black
#> 8   paramters_8 black
#> 9   paramters_9 black
#> 10 paramters_10 black

p = ggplot(df, aes(y = parameters)) + theme(axis.text.y = element_markdown(color = df$color))
q = p + scale_y_discrete(guide = guide_axis(check.overlap = T))

Created on 2021-09-21 by the reprex package (v2.0.0)

ADGN
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1 Answers1

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I don't think the aim of ggtext is to allow vectorised colour assignments through the theme elements. It instead offers to interpret (a limited set of) markdown/html tags in the labels, so if you want one specific label to be red, you should construct the html tag for red text for it.

library(ggplot2)
library(ggtext)
#> Warning: package 'ggtext' was built under R version 4.1.1

N              = 10
df             = data.frame(parameters = paste("paramters", seq(N), sep = "_"))
df$parameters  = factor(df$parameters, levels = df$parameters, ordered = T)
best           = 5

levels(df$parameters) = ifelse(
  levels(df$parameters) == paste("paramters", best, sep = "_"),
  paste0("<span style='color:red'>",   levels(df$parameters), "</span>"),
  paste0("<span style='color:black'>", levels(df$parameters), "</span>")
)


(p = ggplot(df, aes(y = parameters)) + 
  theme(axis.text.y = element_markdown()))


(q = p + 
  scale_y_discrete(guide = guide_axis(check.overlap = T)))

Created on 2021-09-21 by the reprex package (v2.0.1)

teunbrand
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  • This is perfect, thank you very much! – ADGN Sep 21 '21 at 17:17
  • Sorry I was to quick! The solution is almost perfect. However, now, if I raise N to let say 75, the labels can overlap. `guide_axis(check.overlap = T)` is not working anymore. – ADGN Sep 21 '21 at 17:30
  • Ah yes I see, it seems that the gridtext grobs don't support that argument, which is unfortunate. – teunbrand Sep 21 '21 at 17:46
  • Sorry, which argument is not supported by gridtext grobs? – ADGN Sep 21 '21 at 18:03
  • For example `gridtext::richtext_grob`, which is how `element_markdown()` interacts with the grid system. – teunbrand Sep 21 '21 at 18:10
  • Thank you, it was really helpful. I kind of find a workaround based on this [https://stackoverflow.com/questions/30035955/dynamically-formatting-individual-axis-labels-in-ggplot2], which only uses `scale_y_discrete`. However, the original issue is not completely solved as now coloring in red is replaced but putting in bold. But it is fined by me. – ADGN Sep 22 '21 at 09:44