箭头标记ggplot2中的方向

Question

我用这段R代码制作了biplot :

set.seed(12345)
require(ggplot2)
AData <- data.frame(Glabel=LETTERS[1:7], A=rnorm(7, mean = 0, sd = 1), B=rnorm(7, mean = 0, sd = 1))
TData <- data.frame(Tlabel=LETTERS[11:20], A=rnorm(10, mean = 0, sd = 1), B=rnorm(10, mean = 0, sd = 1))
i <- 2
j <- 3
p <- ggplot(data=AData, aes(AData[, i], AData[, j])) + geom_point() + theme_bw()
p <- p + geom_text(aes(data=AData, label=Glabel), size=3, vjust=1.25, colour="black")
p <- p + geom_segment(data = TData, aes(xend = TData[ ,i], yend=TData[ ,j]),
              x=0, y=0, colour="black",
              arrow=arrow(angle=25, length=unit(0.25, "cm")))
p <- p + geom_text(data=TData, aes(x=TData[ ,i], y=TData[ ,j], label=Tlabel), size=3, vjust=1.35, colour="black")

产量

一切都很好,除了箭头标签.我希望标签位于箭头的末端,与箭头的方向相同.任何想法和/或解决方案.提前致谢.

Answer 1

两种可能性:

p <- p + geom_text(data=TData, aes(x=1.2*TData[ ,i], 
                                   y=1.2*TData[ ,j], 
                  label=Tlabel), size=3, vjust=0, colour="black")
p
#-----------------------------------
p <- p + geom_text(data=TData, aes(x=TData[ ,i] +.1*sign(TData[ ,i]), 
                                   y=TData[ ,j]+.1*sign(TData[ ,j]), 
                  label=Tlabel), size=3, vjust=0, colour="black")
p

第一个标签离开箭头的距离随着"强度"而变化,而第二个标签在图形标绘比例上保持固定距离(可能是优选的解决方案和下面所示的解决方案).

最后是一个完全"三角化"的版本,它将使标签与箭头完全相同.(符号(.)参数的相同性是反正切值的约定的结果.雅做你做的事情.):

p <- ggplot(data=AData, aes(AData[, i], AData[, j])) + geom_point() + theme_bw()
p <- p + geom_text(aes(data=AData, label=Glabel), size=3, vjust=1.25, colour="black")
p <- p + geom_segment(data = TData, aes(xend = TData[ ,i], yend=TData[ ,j]),
              x=0, y=0, colour="black",
              arrow=arrow(angle=25, length=unit(0.25, "cm")))
p <- p + geom_text(data=TData, 
            aes(x=TData[ ,i] +.1*cos(atan(TData[ ,j]/TData[ ,i]))*sign(TData[ ,i]), 
                y=TData[ ,j] +.1*sin(atan(TData[ ,j]/TData[ ,i]))*sign(TData[ ,i]), 
            label=Tlabel), size=3, vjust=0, colour="red")