Add % labels to pie chart ggplot2 after specifying factor orders

Question

I have a data frame from which I want to make a pie chart that shows the % label

Here's what I did first

SubSegment<- c('S1','S2','S3','S4')
v <- c(100, 300, 500, 200)
df<- cbind.data.frame(SubSegment, v)

#calculations for % labels in chart
df <- df %>% 
  arrange(desc(SubSegment)) %>%
  mutate(prop = v / sum(df$v)) %>%
  mutate(ypos = cumsum(prop)- 0.5*prop ) %>%
  mutate(label= prop*1)
df[5] = sapply(df[5], function(x) scales::percent(x, accuracy = 0.1))

plot.ex <- ggplot(df, aes(x = "", y = prop, fill = SubSegment)) +
  geom_bar(width = 1, stat = "identity", color="white", alpha=0.8) +
  coord_polar("y", start = 0) +
  theme_void() + 
  geom_text(aes(y = ypos, label = label), size=3, color = "white") +
  scale_fill_brewer(palette="Set1")

The result:

As you can see, the labels look great and they are on the right place but it bothers me that the order of the factors is alphabetical, I would want the company with the biggest value to show first in the legend so I added one line of code before the plot:

df$SubSegment <- factor(df$SubSegment, levels=df$SubSegment[order(-(df$prop))], ordered=TRUE)

After doing that the order of the factors in the legend of the plot is as I wanted but the labels get all messed up (they don't move accordingly with the pie pieces).

Here's what my second pie chart looks like:

Basically I want to know how to edit my ypos line so that the labels will move accordingly when the pie pieces move.

Try `pie(df$v, col=2:5, labels=paste0(round(proportions(df$v)*100, 1), '%'));legend('right', col=2:5, leg=df$SubSegment, pch=15)`. — jay.sf, Feb 13 '22 at 12:47
Does this answer your question? [pie chart with ggplot2 with specific order and percentage annotations](https://stackoverflow.com/questions/47752037/pie-chart-with-ggplot2-with-specific-order-and-percentage-annotations) — benson23, Feb 13 '22 at 13:01

tivd · Answer 1 · 2022-02-13T13:09:39.200

You want to show the subsegments based on their proportions and therefore should calculate your ypos based on your proporations. This can be simply done by changing your arrange() line:

df <- df %>% 
  mutate(prop = v / sum(df$v), 
         label= scales::percent(prop, accuracy = 0.1)) %>% 
  arrange(prop) %>% 
  mutate(ypos = cumsum(prop)- 0.5*prop, 
         SubSegment = factor(SubSegment, levels=SubSegment[order(-(prop))], ordered=TRUE))



ggplot(df, aes(x = "", y = prop, fill = SubSegment)) +
  geom_bar(width = 1, stat = "identity", color="white", alpha=0.8) +
  coord_polar("y", start = 0) +
  theme_void() + 
  geom_text(aes(y = ypos, label = label), size=3, color = "white") +
  scale_fill_brewer(palette="Set1")

Add % labels to pie chart ggplot2 after specifying factor orders

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