Add count values on top of gghistogram

Question

I've made a histogram for the different age groups in my data:

> dput(Agedata[1:20,])

structure(list(samples = c("Pt1", "Pt10", "Pt101", "Pt103", "Pt106", 
"Pt11", "Pt17", "Pt18", "Pt2", "Pt24", "Pt26", "Pt27", "Pt28", 
"Pt29", "Pt3", "Pt30", "Pt31", "Pt34", "Pt36", "Pt37"), resp = c("NoResponse", 
"NoResponse", "Response", "NoResponse", "NoResponse", "NoResponse", 
"NoResponse", "Response", "NoResponse", "NoResponse", "NoResponse", 
"NoResponse", "NoResponse", "NoResponse", "Response", "Response", 
"NoResponse", "Response", "NoResponse", "NoResponse"), age = c(58, 
53, 61, 57, 57, 62, 51, 59, 58, 60, 61, 49, 52, 57, 61, 61, 60, 
56, 55, 61), age_group = structure(c(6L, 6L, 7L, 6L, 6L, 7L, 
6L, 6L, 6L, 7L, 7L, 5L, 6L, 6L, 7L, 7L, 7L, 6L, 6L, 7L), levels = c("0-9", 
"10-19", "20-29", "30-39", "40-49", "50-59", "60-69", "70-79", 
"80-89", "90-99"), class = "factor")), row.names = c(NA, 20L), class = "data.frame")

Like this:

library(ggpubr)

gghistogram(Agedata, x = "age_group", bins = 8,
            rug = TRUE,
            color = "resp", fill = "resp", stat = 'count',
            palette = c("red", "green"), main = 'Age ~ Outcome') + ylim(c(0,500)) + theme_bw()

Now how do I add the count values on top of each bin? including the red bins and the green bins?

Answer 1

I think I would use plain old geom_bar here instead of gghistogram. In general, functions like gghistogram make it easier to produce nice results in ggplot with minimal code, but what they lack in ease-of-use they lose in flexibility.

Since your bins are pre-defined rather than being constructed from a continuous variable, your data is a better fit for a bar plot than a histogram. It also allows you to add text via geom_text rather than having to work out what gghistogram is doing internally with its aesthetic mappings first.

ggplot(Agedata, aes(age_group, color = resp)) +
  geom_bar(aes(fill = after_scale(alpha(colour, 0.4)))) +
  geom_text(stat = 'count', position = position_stack(vjust = 1),
            vjust = -0.2,
            aes(label = after_stat(count), group = resp), color = 'black') +
  scale_color_manual(values = c('red2', 'green3')) +
  theme_bw()