为最小-最大范围创建 geom_ribbon

给出以下数据：

df<-data.frame(
  year=(1996:2000),
  a=c(2,1.5,1.5,2,3),
  b=c(2,2,2,3,4),
  c=c(2,3,3,1,1))

与 ggplot:

  ggplot(df,aes(x=year))+
    geom_line(aes(y=a))+
    geom_line(aes(y=b))+
    geom_line(aes(y=c))

看起来像这样：

how. can I create a ribbon that shows always the area between minimum and maximum (think of it like a min-max-range), to get it look like this:

首先计算最小值和最大值怎么样：

df$min <- apply(df[, -1], 1, min)
df$max <- apply(df[, -1], 1, max)

然后简单地绘制功能区：

ggplot(df, aes(x = year, ymin = min, ymax = max)) + geom_ribbon()