Any automated process for recoloring or adding indicators to axis labels based on categories in ggplot?

Question

I have made some bar plots in ggplots and was hoping to indicate that each bar is part of larger category via the axis label. Like the plot below for example:

I understand that I could use aesthetics to recolor the axis labels manually, or mutate the dataframe to call specific colors. (See this post for an example: ggplot color axis labels based on variable)

But is there no automated process in ggplots to do this and generate a legend, similar to fill/ scale_fill?

Answer 1

We can use the ggside package for this. A simple tutorial can be found here.

Dummy input from the package gapminder:

Since I don't have your dataframe, I'll use the gapminder dataset as an example.

library(gapminder)

test_df <- gapminder %>% 
  group_by(country) %>% 
  slice_head(n = 3) %>% 
  arrange(country) %>% 
  head(n = 10)

# A tibble: 10 × 6
# Groups:   country [4]
   country     continent  year lifeExp      pop gdpPercap
   <fct>       <fct>     <int>   <dbl>    <int>     <dbl>
 1 Afghanistan Asia       1952    28.8  8425333      779.
 2 Afghanistan Asia       1957    30.3  9240934      821.
 3 Afghanistan Asia       1962    32.0 10267083      853.
 4 Albania     Europe     1952    55.2  1282697     1601.
 5 Albania     Europe     1957    59.3  1476505     1942.
 6 Albania     Europe     1962    64.8  1728137     2313.
 7 Algeria     Africa     1952    43.1  9279525     2449.
 8 Algeria     Africa     1957    45.7 10270856     3014.
 9 Algeria     Africa     1962    48.3 11000948     2551.
10 Angola      Africa     1952    30.0  4232095     3521.

ggplot

library(tidyverse)
library(ggside)

ggplot(test_df, aes(country, lifeExp, fill = as.character(year))) + 
  geom_col() + 
  geom_xsidetile(aes(xfill = continent), position = "fill") + 
  scale_xsidey_continuous(breaks = NULL) +
  ggside(x.pos = "bottom", draw_x_on = "main") + 
  theme_ggside_minimal()

^{Created on 2023-03-08 with reprex v2.0.2}