在R中并排绘制几组箱形图 [英] Plotting several groups of box plots side-by-side in R

问题描述

我正在尝试在同一图中绘制两个箱形图，每个都在同一类别中。
我可以分别生成箱线图，但是当我尝试将它们绘制到同一张图上时会陷入困境。

I am trying to plot two box-plots in the same plot, each within the same category. I can generate the boxplots individually, but am stumped when I try to get them onto the same graph.

这是我到目前为止的内容：

Here is what I have so far:

a<-matrix(nrow=100,ncol=3,data=runif(300,max=2))
b<-matrix(nrow=100,ncol=3,data=runif(300,max=1))
colnames(a)<-c("case 1","case 2","case 3")
colnames(b)<-c("case 1","case 2","case 3")
boxplot(cbind(a,b))

此图导致6个箱型图，前3个代表a，然后3个代表b。

This plot results in 6 boxplots, first 3 for a, then 3 for b.

我是否缺少技巧/简单的选项，它会给我
a和b的第一个值，然后是第二个，最后是第三组值，所有绘制方式都只有x轴上的三个刻度，每组三个刻度？

Is there a trick/simple option that I am missing that will give me first value for a and b, then second and finally the third set of values, all plotted in such a way there are is only three ticks on the x-axis, one for each of the sets?

任何指针都会受到赞赏，

Any pointers greatly appreciated,

Iain

推荐答案

boxplot(a, at = 0:2*3 + 1, xlim = c(0, 9), ylim = range(a, b), xaxt = "n")
boxplot(b, at = 0:2*3 + 2, xaxt = "n", add = TRUE)
axis(1, at = 0:2*3 + 1.5, labels = colnames(a), tick = TRUE)

请注意 ylim = range（a，b）参数。绘图比例由第一个命令确定，但是如果b包含a中的值范围之外的值（在这种情况下不是，但是尝试交换a和b），则它们将不在绘图范围内。这就是为什么通常应该在此处指定ylim的原因。

Note the ylim = range(a, b) parameter. The plot scale is determined by the first command, but if b contained values out of range of values in a (not in this case, but try to swap a and b), they would lie out of the plot. That's why in general you should specify the ylim here.

还可以在 axis（）命令，我认为它更好。
如果您不喜欢组之间的空间，请使用 0：2 * 2 而不是 0：2 * 3 ，并适当地更改xlim。

You can also set tick = FALSE in the axis() command, I think it is nicer. If you don't like the space between the groups, use 0:2*2 instead of 0:2*3, and change the xlim appropriatelly.

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