How to align the labels to the middle / center in a donut chart

Question

I'm using geom_textpath to add labels to a double donut chart but the labels are not aligned to the middle.

How can I align the labels in the middle or the center of each segment?

library(magrittr)
library(ggplot2)
library(geomtextpath)
pie_data <- data.frame(category=c('A','B','C','A','B','C'),
                       year=c(2020,2020,2020,2021,2021,2021),
                       sales=c(40,30,20,10,15,10))

pie_data %>% ggplot(aes(x=year,y=sales,fill=category))+
  geom_col(position='fill',width=1,color='white')+
 lims(x=c(2018,2023))+
  geom_textpath(position='fill',angle=90,hjust=2,alpha=1,
                aes(color=factor(year),
                    label=paste0(category,':',sales)))+
 coord_polar(theta = 'y')+
  
  theme_void()

Answer 1

To position the labels when using position="fill" it's good to know that position_fill has a argument vjust to position the labels in the middle of the bars using vjust = .5:

library(magrittr)
library(ggplot2)
library(geomtextpath)

pie_data <- data.frame(
  category = c("A", "B", "C", "A", "B", "C"),
  year = c(2020, 2020, 2020, 2021, 2021, 2021),
  sales = c(40, 30, 20, 10, 15, 10)
)

pie_data %>% ggplot(aes(x = year, y = sales, fill = category)) +
  geom_col(position = "fill", width = 1, color = "white") +
  lims(x = c(2018, 2023)) +
  geom_textpath(
    position = position_fill(vjust = .5), angle = 90, alpha = 1,
    aes(
      color = factor(year),
      label = paste0(category, ":", sales)
    )
  ) +
  coord_polar(theta = "y") +
  theme_void()