从Box图中删除多个级别的空白级别

Question

我有一个包含多个级别的盒子图d $ a + d $ b

d = data.frame(value = c(1,2,3,100), a = c("A","A","B","A"), b = c("C","D","C","C") )
boxplot(d$value ~ d$a + d$b, horizontal = TRUE)

当您运行该代码时，您会看到B.D组合仍然显示但它是空的。如何删除它？

这只是一个玩具的例子。实际上我有40多种组合，并且不想手动删除空白组合。

Answer 1

您可以先使用interaction（及其drop参数）创建data.frame的新列，然后绘制它：

d <- data.frame(value = c(1,2,3,100), a = c("A","A","B","A"), b = c("C","D","C","C"))
d <- within(d, interaction <- interaction(a, b, drop = TRUE))
boxplot(value ~ interaction, data = d, horizontal = TRUE)