Insert legend into geom_area plot

Question

Is it possible to insert the legend of a ggplot::geom_area() into the respective areas?

I.e., I would like to change

to:

(source for the plot: https://www.geeksforgeeks.org/stacked-area-chart-with-r/)

Answer 1

You can use geom_text with position_fill. You will also need to filter to include only a single year of your choosing:

ggplot(data, aes(x = year, y = percentage, fill = group)) +
  geom_area(alpha = 0.8, size = 0.5, colour = "white") +
  geom_text(aes(label = group), position = position_fill(vjust = 0.5),
            data = . %>% filter(year == 2018)) +
  scale_fill_viridis(discrete = TRUE) + 
  theme_ipsum() +
  ggtitle("Percentage Stacked-Area Plot")

---

Data used

We would normally ask that questions contain the necessary data and code directly rather than pointing to external links. External links may change, and there have been instances of spammy or malicious links. I have harvested the relevant code from the link provided for others to reproduce the plot here:

library(tidyverse)
library(viridis)
library(hrbrthemes)

set.seed(1)

group <- rep(c("NORTH", "SOUTH", "EAST", "WEST"), times = 4)  
year  <- as.numeric(rep(seq(2017, 2020), each = 4)) 
price <- runif(16, 50, 100)
data  <- data.frame(year, price, group)

data <- data  %>%
  group_by(year, group) %>%
  summarise(n = sum(price)) %>%
  mutate(percentage = n / sum(n))