r - 如何在计算框之前让 geom_boxplot 应用 y 限制？

Question

这是一个箱线图:

qplot(cyl, mpg, data=mtcars) +
  geom_boxplot() +
  scale_y_continuous()

看起来像这样:

现在我在 y 轴上添加限制:

qplot(cyl, mpg, data=mtcars) +
  geom_boxplot() +
  scale_y_continuous(limits=c(0,20))

整个画面都变了:

如何获得与第一张相同的图片，只是“视口(viewport)”显示 y=0 到 20？

还有..第二张图片是什么？看起来确实缺少数据(例如:cyl=4 的 3-4 点)。

Answer 1

从 joran 的评论来看，这是可行的:

qplot(cyl, mpg, data=mtcars) +
  geom_boxplot() +
  coord_cartesian(ylim=c(0,20))

来自 the docs :

There are two ways of zooming the plot display: with scales or with coordinate systems. They work in two rather different ways.

Setting the limits on a scale will throw away all data that's not inside these limits. This is equivalent to plotting a subset of the original data

Setting the limits on the coordinate system performs a visual zoom the data is unchanged, and we just view a small portion of the original plot.

谢谢乔兰!