更改ggplot2中堆积填充列的顺序

Question

我想更改堆积条形图的顺序。例如，mpg我要订购c("4", "r", "f")

改变因素水平的唯一方法是吗？

library(ggplot2)
library(dplyr)
s <- ggplot(mpg, aes(fl, fill=drv)) + geom_bar(position="stack")
s

Answer 1

输入数据的结构为字符：

str(mpg$drv)

> chr [1:234] "f" "f" "f" "f" "f" "f" "f" "4" "4" "4" "4" "4" "4" "4" "4" "4" "4" "4" "r" "r" "r" "r" "r" "r" "r" "r" "r" "r" "4" "4" "4" "4" "f" "f" "f" "f" "f" "f" "f" "f" "f" "f" "f" ...

ggplot将自动将字符串转换为因子。您可以看到默认顺序如下，并且此转换按字母顺序对它们进行排序：

levels(as.factor(mpg$drv))
> "4" "f" "r"

要在不更改原始数据的情况下对条形图重新排序，您可以在图自身中重构变量：

ggplot(mpg, aes(fl, fill = factor(drv, levels=c("4", "r", "f")))) + 
  geom_bar(position="stack") +
  labs(fill = "Drive")

比较结果：