带百分比标签的堆积条形图

Question

我创建了一个堆积的条形图，其中的条形表示人口的百分比。我想将标签添加到65岁以上的类别（如果不可能仅针对1个类别，则为所有3个类别添加标签），以显示每年的％值。如果添加geom_text(label = datm$value)，则条形会变得非常小，因为标签代表的是绝对值而不是百分比。这是我的代码：

dat <- read.table(text = "2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
0-20 24.0 23.9 23.7 23.5 23.3 23.1 22.9 22.7 22.5 22.3 22.2
20-65 61.3 61.2 61.0 60.9 60.5 60.1 59.8 59.6 59.3 59.1 59.0
65+ 14.8 15.0 15.3 15.6 16.2 16.8 17.4 17.7 18.2 18.5 18.8", sep = " ", header = TRUE)

library(reshape)
datm <- melt(cbind(dat, ind = rownames(dat)), id.vars = c('ind'))

library(scales)
library(ggplot2)
ggplot(datm,aes(x = variable, y = value, fill = ind)) + 
  geom_bar(position = "fill",stat = "identity") + 
  scale_x_discrete(labels = c('2008', '2009', '2010', '2011', '2012', '2013', 
                              '2014', '2015', '2016', '2017', '2018')) + 
  scale_y_continuous(labels = percent_format()) + 
  xlab('Year') + 
  ylab('% of population') + 
  ggtitle('Demographic trend in the Netherlands') + 
  scale_fill_manual(values = c("green", "blue", "darkgray"))

Answer 1

您可以尝试一下。以下评论中的解释：

library(dplyr)

# calculate percentage within each year
datm2 <- datm %>%
  group_by(variable) %>%
  mutate(p = value / sum(value)) %>%
  ungroup()

> head(datm2)
# A tibble: 6 x 4
  ind   variable value     p
  <fct> <fct>    <dbl> <dbl>
1 0-20  X2008     24   0.240
2 20-65 X2008     61.3 0.612
3 65+   X2008     14.8 0.148
4 0-20  X2009     23.9 0.239
5 20-65 X2009     61.2 0.611
6 65+   X2009     15   0.150

ggplot(datm2, aes(x = variable, y = value, fill = ind)) + 
  geom_col(position = "fill") + # geom_col is equivalent to geom_bar(stat = "identity")
  geom_text(aes(label = scales::percent(p),          # add layer for percentage values
                alpha = ifelse(ind == "65+", 1, 0)), # only visible for 65+ category
            position = position_fill(vjust = 0.5)) + # follow barplot's position
  scale_x_discrete(labels = c('2008', '2009', '2010', '2011', '2012', '2013', 
                              '2014', '2015', '2016', '2017', '2018')) + 
  scale_y_continuous(labels = percent_format()) + 
  scale_alpha_identity() +
  xlab('Year') + 
  ylab('% of population') + 
  ggtitle('Demographic trend in the Netherlands') + 
  scale_fill_manual(values = c("green", "blue", "darkgray"))