How to use percent as a label in a laid out line chart?

Question

I am trying to display percentages as labels inside bars of an overlaid graph in ggplot2. I found another post from 3 years ago, but I can’t reproduce it: How to draw stacked columns in ggplot2 showing percentages for a group?

The answer to this post is almost what I'm trying to do.

Here is a simple example of my data:

df = data.frame('sample' = c('cond1','cond1','cond1','cond2','cond2','cond2','cond3','cond3','cond3','cond4','cond4','cond4'),
                'class' = c('class1','class2','class3','class1','class2','class3','class1','class2','class3','class1','class2','class3'))
ggplot(data=df, aes(x=sample, fill=class)) + 
    coord_flip() +
    geom_bar(position=position_fill(reverse=TRUE), width=0.7)

I would like for each bar to show a percentage / share, so in this case they will all be 33%. In fact, it would be nice if the values ​​were calculated on the fly, but if necessary, I can manually transfer percentages. Can anyone help?

: ? , width position_fill(), .

!

EDIT:

, , ( ), , . , , :

df = data.frame('sample' = c('cond1','cond1','cond1','cond2','cond2','cond2','cond3','cond3','cond3','cond4','cond4','cond4','cond1'),
                'class' = c('class1','class2','class3','class1','class2','class3','class1','class2','class3','class1','class2','class3','class2'))

, /.

Answer 1

, OP, . , data.table, count , ggplot:

library(data.table)
library(scales)
dt <- setDT(df)[,list(count = .N), by = .(sample,class)][,list(class = class, count = count,
                percent_fmt = paste0(formatC(count*100/sum(count), digits = 2), "%"),
                percent_num = count/sum(count)
                ), by = sample]

ggplot(data=dt, aes(x=sample, y= percent_num, fill=class)) +   
  geom_bar(position=position_fill(reverse=TRUE), stat = "identity", width=0.7) +
  geom_text(aes(label = percent_fmt),position = position_stack(vjust = 0.5)) + coord_flip()

: , y . , position_stack(vjust = 0.5):

dt <- setDT(df)[,list(count = .N), by = .(sample,class)][,list(class = class, count = count,
               percent_fmt = paste0(formatC(count*100/sum(count), digits = 2), "%"),
               percent_num = count/sum(count),
               cum_pct = cumsum(count/sum(count)),
               label_y = (cumsum(count/sum(count)) + cumsum(ifelse(is.na(shift(count/sum(count))),0,shift(count/sum(count))))) / 2
), by = sample]

ggplot(data=dt, aes(x=sample, y= percent_num, fill=class)) +   
  geom_bar(position=position_fill(reverse=TRUE), stat = "identity", width=0.7) +
  geom_text(aes(label = percent_fmt, y = label_y)) + coord_flip()

Answer 2

scales

library(scales)
ggplot(data=df, aes(x=sample, fill=class)) +
  coord_flip() +
  geom_bar(position=position_fill(reverse=TRUE), width=0.7) +
  scale_y_continuous(labels =percent_format())

Answer 3

, , dplyr, :

:

options(stringsAsFactors = F)

df = data.frame(sample = c('cond1','cond1','cond1','cond2','cond2','cond2','cond3','cond3','cond3','cond4','cond4','cond4'), 
                class = c('class1','class2','class3','class1','class2','class3','class1','class2','class3','class1','class2','class3'))

library(dplyr) 
library(scales)

df%>%
  # count how often each class occurs in each sample.
  count(sample, class)%>% 
  group_by(sample)%>%
  mutate(pct = n /sum(n))%>%
  ggplot(aes(x = sample, y = pct, fill = class)) + 
  coord_flip() +
  geom_col(width=0.7)+
  geom_text(aes(label = paste0(round(pct * 100), '%')),
            position = position_stack(vjust = 0.5))