r - 在ggplot2中的叠加条上方绘制总和值

如何在ggplot2的堆叠条上方绘制每个类的总和值（在我的情况下：a = 450，b = 150，c = 290，d = 90）？这是我的代码：

#Data
hp=read.csv(textConnection(
"class,year,amount
a,99,100
a,100,200
a,101,150
b,100,50
b,101,100
c,102,70
c,102,80
c,103,90
c,104,50
d,102,90"))
hp$year=as.factor(hp$year)

#Plotting
p=ggplot(data=hp)
p+geom_bar(binwidth=0.5,stat="identity")+
aes(x=reorder(class,-value,sum),y=value,label=value,fill=year)+
theme()

最佳答案

您可以通过创建每个班级总计的数据集来做到这一点（可以通过多种方式完成，但我更喜欢dplyr）：

library(dplyr)
totals <- hp %>%
    group_by(class) %>%
    summarize(total = sum(value))

然后使用geom_text作为数据集将totals图层添加到绘图中：

p + geom_bar(binwidth = 0.5, stat="identity") +
    aes(x = reorder(class, -value, sum), y = value, label = value, fill = year) +
    theme() +
    geom_text(aes(class, total, label = total, fill = NULL), data = totals)

您可以使用vjust参数使文本高于或低于条形图的顶部，或者仅向total添加一些值即可：

p + geom_bar(binwidth = 0.5, stat = "identity") +
    aes(x = reorder(class, -value, sum), y = value, label = value, fill = year) +
    theme() +
    geom_text(aes(class, total + 20, label = total, fill = NULL), data = totals)