ggplot2 pie chart bad position of labels

Question

Sample data

data <- data.frame(Country = c("Mexico","USA","Canada","Chile"), Per = c(15.5,75.3,5.2,4.0))

I tried set position of labels.

ggplot(data =data) +
geom_bar(aes(x = "", y = Per, fill = Country), stat = "identity", width = 1) +
coord_polar("y", start = 0) + 
theme_void()+ 
geom_text(aes(x = 1.2, y = cumsum(Per), label = Per)) 

But pie chart actually look like:

Answer 1

You have to sort the data before calculating the cumulative sum. Then, you can optimize label position, eg by subtracting half of Per :

library(tidyverse)
data %>% 
  arrange(-Per) %>% 
  mutate(Per_cumsum=cumsum(Per)) %>% 
ggplot(aes(x=1, y=Per, fill=Country)) +
  geom_col() +
  geom_text(aes(x=1,y = Per_cumsum-Per/2, label=Per)) +
  coord_polar("y", start=0) + 
  theme_void()

PS: geom_col uses stat_identity by default: it leaves the data as is.

Or simply use position_stack

data %>% 
  ggplot(aes(x=1, y=Per, fill=Country)) +
  geom_col() +
  geom_text(aes(label = Per), position = position_stack(vjust = 0.5))+
  coord_polar(theta = "y") + 
  theme_void()

From the help:

# To place text in the middle of each bar in a stacked barplot, you
# need to set the vjust parameter of position_stack()