library(ggplot2)

df <- data.frame(trt=c("TAVERN","Long Term Care","Grocery Store","Restaurant"),outcome=c("a","b","c","d"))

ggplot(df,aes(trt,outcome)) + 
  geom_col() +
  geom_point(colour = 'red') +
  ggtitle("Failing rate in different facility types") + 
  labs(x="Facility type",y="Failing rate") + 
  theme(panel.background = element_blank()) +
  scale_color_manual(values = c("purple","green","red","orange"))

我尝试手动更改ggplot中的颜色。

但是我没有这样做。真的很困惑。

问题。如何依次设置ggplot()函数的参数 改变条形的颜色？