Multirow axis labels with nested grouping variables

Question

I would like the levels of two different nested grouping variables to appear on separate lines below the plot, and not in the legend. What I have right now is this code:

Answer 1

Here's another solution using a package I'm working on for grouped bar charts (ggNestedBarChart):

data <- read.table(text = "Group Category Value
                   S1 A   73
                   S2 A   57
                   S3 A   57
                   S4 A   57
                   S1 B   7
                   S2 B   23
                   S3 B   57
                   S1 C   51
                   S2 C   57
                   S3 C   87", header = TRUE)

devtools::install_github("davedgd/ggNestedBarChart")
library(ggNestedBarChart)
library(scales)

p1 <- ggplot(data, aes(x = Category, y = Value/100, fill = Category), stat = "identity") +
  geom_bar(stat = "identity") +
  facet_wrap(vars(Category, Group), strip.position = "top", scales = "free_x", nrow = 1) +
  theme_bw(base_size = 13) +
  theme(panel.spacing = unit(0, "lines"),
        strip.background = element_rect(color = "black", size = 0, fill = "grey92"),
        strip.placement = "outside",
        axis.text.x = element_blank(),
        axis.ticks.x = element_blank(),
        panel.grid.major.y = element_line(colour = "grey"),
        panel.grid.major.x = element_blank(),
        panel.grid.minor = element_blank(),
        panel.border = element_rect(color = "black", fill = NA, size = 0),
        panel.background = element_rect(fill = "white"),
        legend.position = "none") + 
  scale_y_continuous(expand = expand_scale(mult = c(0, .1)), labels = percent) + 
  geom_text(aes(label = paste0(Value, "%")), position = position_stack(0.5), color = "white", fontface = "bold")

ggNestedBarChart(p1)

ggsave("p1.png", width = 10, height = 5)

Note that ggNestedBarChart can group as many levels as necessary and isn't limited to just two (i.e., Category and Group in this example). For instance, using data(mtcars):

Code for this example is on the GitHub page.