如何用 2 列制作 R 图例？

Question

我想在我的图上做一个图例，它是由 plot() 函数生成的。原始的 legend() 函数将生成一个只有 1 列的列表。我怎样才能制作一个有 2 列的图例？

Answer 1

检查这个：

library(lattice)

myPCH <- 15:17
Data  <- rnorm(50)
Index <- seq(length(Data))

xyplot(Data ~ Index, 
       pch = myPCH, col=1:2,
       key = list(space = "right", adj=1,
                  text = list(c("a", "b", "c"), cex=1.5),
                  points = list(pch = myPCH),
                  points = list(pch = myPCH,col=2)))

Answer 2

对于标准图，我无法在对 legend 的一次调用中找到一种方法。

这里有一个选项，绘制两个单独的图例：一个带有线和点，一个带有标签。 x.intersp 可用于调整标签和线条之间的距离。

plot(cumsum(runif(n = 100)))

# draw legend with lines and point but without labels and box. x.intersp controls horizontal distance between lines
L = legend(x = 'bottom', legend = rep(NA,4), col=1:2, lty=c(1,1,2,2), ncol=2, bty='n', x.intersp=0.5, pch=c(1,2,1,2), inset=0.02)

# use position data of previous legend to draw legend with invisble lines and points but with labels and box. x.intersp controls distance between lines and labels
legend(x = L$rect$left, y = L$rect$top, legend = c('Group A', 'Group B'), col=rep(NA,2), lty=c(1,1), ncol=1, x.intersp = 3, bg = NA)

如何用 2 列制作 R 图例？

How to make R legend with 2 columns?

plot

r

legend