Add percentage labels to a stacked barplot

Question

I have successfully made a stacked barplot in R where the percentages add up to 100% for several different categories. I made an example dataframe here.

example.Category<- c("Cat1","Cat2","Cat3","Cat4","Cat5","Cat6")
percent.good <- c(.25,.29,.45,.5,.8,.82)
example.data <- data.frame(example.Category,percent.good)
example.data$percent.bad <- (1-example.data$percent.good)

The dataframe looks like this.

     example.Category percent.good percent.bad
1             Cat1         0.25        0.75
2             Cat2         0.29        0.71
3             Cat3         0.45        0.55
4             Cat4         0.50        0.50
5             Cat5         0.80        0.20
6             Cat6         0.82        0.18

I then used melt from the reshape package to get this...

example.melt <- melt(example.data, id.vars="example.Category")

   example.Category     variable value
1              Cat1 percent.good  0.25
2              Cat2 percent.good  0.29
3              Cat3 percent.good  0.45
4              Cat4 percent.good  0.50
5              Cat5 percent.good  0.80
6              Cat6 percent.good  0.82
7              Cat1  percent.bad  0.75
8              Cat2  percent.bad  0.71
9              Cat3  percent.bad  0.55
10             Cat4  percent.bad  0.50
11             Cat5  percent.bad  0.20
12             Cat6  percent.bad  0.18

Then I used ggplot to make a stacked barplot displaying these percentages.

ggplot(example.melt, aes(x=example.Category, y=value, fill = variable)) +
  geom_bar(position = "fill", stat = "identity",color='black',width=0.9) +
  scale_y_continuous(labels = scales::percent) +
  geom_text(aes(label = paste0((example.data$percent.good && example.data$percent.bad)*100), '%'),position = position_dodge(width = .9),size = 3)

This yields this graph, which is what I want, except for the way it labels.

What I want to do is have percentage labels for each color on each stacked bar, and I have no idea how to do that and am certain that I didn't do it right. All I managed to do was somehow create another category that has some '100's around. How would I get the percent labels to appear on this graph for each part of the bar?

I hope this isn't redundant/asked before. Thanks.

Solution 1

You could do something like this...

#set positions for labels
example.melt$labelpos <- ifelse(example.melt$variable=="percent.bad",
                         example.melt$value/2, 1 - example.melt$value/2)
ggplot(example.melt, aes(x=example.Category, y=value, fill = variable)) +
  geom_bar(position = "fill", stat = "identity",color='black',width=0.9) +
  scale_y_continuous(labels = scales::percent) +
#use positions to plot labels
  geom_text(aes(label = paste0(100*value,"%"),y=labelpos),size = 3)

Solution 2

This would give you the asnwer:

ggplot(example.melt, aes(x=example.Category, y=value, fill = variable)) +
  geom_bar(position = "fill", stat = "identity",color='black',width=0.9) +
  scale_y_continuous(labels = scales::percent) +
  geom_text(aes(label = paste0(value*100,"%")), 
            position = position_stack(vjust = 0.5), size = 2)

Plot would look like this: