I have the following data about American and German teenagers’ coding skills. I can easily display their bar plots, but I need to present the total number of teenagers from each country as well.
DF <- data.frame(code = rep(c("A","B","C"), each = 2),
Freq = c(441,121,700,866,45,95),
Country = rep(c("USA","Germany"),3),
Total = rep(c(1186,1082),3))
ggplot(DF, aes(code, Freq, fill = code)) + geom_bar(stat = "identity", alpha = 0.7) +
facet_wrap(~Country, scales = "free") +
theme_bw() +
theme(legend.position="none")
For example, instead of presenting the default legend for the code, I could replace it with the Country and the Total. Your help is appreciated
>Solution :
Here’s what I would suggest:
library(dplyr); library(ggplot2)
DF %>%
add_count(Country, wt = Total) %>%
mutate(Country_total = paste0(Country, ": Total=", n)) %>%
ggplot(aes(code, Freq, fill = code)) + geom_bar(stat = "identity", alpha = 0.7) +
facet_wrap(~Country_total, scales = "free") +
theme_bw() +
theme(legend.position="none")
To do what you’re requesting would take a different approach, since the data you’re describing would not strictly be a ggplot2 legend (which explains how one of the variables is mapped to one of the graph aesthetics), rather it would be a table or annotation that is displayed alongside the plot. This could be generated separately and added to the figure using patchwork or grid packages.
For instance:
library(patchwork); library(gridExtra)
ggplot(DF, aes(code, Freq, fill = code)) + geom_bar(stat = "identity", alpha = 0.7) +
facet_wrap(~Country, scales = "free") +
theme_bw() +
theme(legend.position="none") +
tableGrob(count(DF, Country, wt = Total)) +
plot_layout(widths = c(2,1))
