R：点和线颜色不同的图例（对于同一图例项）

使用legend（）函数可以使点和线具有不同的颜色吗？我觉得我错过了一些很明显的东西。

pt.bg

选项可以更改背景颜色，但我没有看到

pt.fg

选项

当分别使用不同颜色的lines（）和points（）命令并希望图例表示打印内容时，会出现这种情况

我认为使用

merge

选项是可能的，但我显然不太明白这是为了什么

例如：

plot( 0, type="n", xlim=c(0,5), ylim=c(0,5) )
A <- matrix( c( c(1,2,3,4), c(2,1,2,4)), ncol=2 )
B <- matrix( c( c(1,2,3,4), c(1,3,3,2)), ncol=2 )
lines( A, col="red" )
points( A, col="blue", pch=15 )
lines( B, col="green" )
points( B, col="purple", pch=17 )

legend( x="topleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("red","green"), lwd=1, lty=c(1,2), 
        pch=c(15,17) )

legend( x="bottomleft", 
        legend=c("Red line","blue points","Green line","purple points"),
        col=c("red","blue","green","purple"), lwd=1, lty=c(1,NA,2,NA),
        pch=c(NA,15,NA,17) )

legend( x="left", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("red","green"), lwd=1, lty=c(1,2), pch=c(15,17), merge=FALSE )

legend( x="bottomright", 
        legend=c("Red line","blue points","Green line","purple points"), 
        col=c("red","blue","green","purple"), lwd=1, lty=c(1,NA,2,NA), 
        pch=c(NA,15,NA,17), merge=FALSE )

legend( x="topright", 
        legend=c("Red line, blue points","Green line, purple points"), 
        col=c("red","blue","green","purple"), lwd=1, lty=c(1,2), 
        pch=c(15,17), merge=FALSE )

---

您可以通过两次调用

legend

，第一次绘制线条，然后第二次调用在顶部绘制不可见的线条，但以所需的颜色绘制点：

plot( 0, type="n", xlim=c(0,5), ylim=c(0,5) )
A <- matrix( c( c(1,2,3,4), c(2,1,2,4)), ncol=2 )
B <- matrix( c( c(1,2,3,4), c(1,3,3,2)), ncol=2 )
lines( A, col="red" )
points( A, col="blue", pch=15 )
lines( B, col="green" )
points( B, col="purple", pch=17 )

legend( x="topleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("red","green"), lwd=1, lty=c(1,2), 
        pch=c(NA,NA) )

legend( x="topleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("blue","purple"), lwd=1, lty=c(0,0), 
        pch=c(15,17) )

---

当然，这只能从左边正确排列。如果你想让绘图在一个右角，那么将第一次调用的返回值保存到

legend

，并将其用于第二次调用中的位置。

我猜你必须自己动手/翻滚……太棒了！把它作为答案贴出来。我没有看到你的解决方案。最后一个建议是避免两份文本相互重叠打印，这只适用于“左”对齐的图例。另一个技巧是使用

text.col

选项，该选项也适用于“右”对齐的图例。在第一个调用中使用

text.col=“white”

，在第二个调用中使用

text.col=“black”

调用

legend

。对于水平对齐的图例也不起作用@Simon在问题中发布了他自己的解决方案（修改legend函数本身），它非常适合我。

LEGEND( x="bottomleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("red","green"), 
        lwd=1, lty=c(1,2), pch=c(15,17) )

LEGEND( x="bottomright", 
        legend=c("Red line, blue points","Green line, purple points"),
        pt.col=c("blue","purple"), line.col=c("red","green"),
        lwd=1, lty=c(1,2), pch=c(15,17) )

plot( 0, type="n", xlim=c(0,5), ylim=c(0,5) )
A <- matrix( c( c(1,2,3,4), c(2,1,2,4)), ncol=2 )
B <- matrix( c( c(1,2,3,4), c(1,3,3,2)), ncol=2 )
lines( A, col="red" )
points( A, col="blue", pch=15 )
lines( B, col="green" )
points( B, col="purple", pch=17 )

legend( x="topleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("red","green"), lwd=1, lty=c(1,2), 
        pch=c(NA,NA) )

legend( x="topleft", 
        legend=c("Red line, blue points","Green line, purple points"),
        col=c("blue","purple"), lwd=1, lty=c(0,0), 
        pch=c(15,17) )

legend( x="topleft", 
        legend=c("",""),
        col=c("blue","purple"), lwd=1, lty=c(0,0), 
        pch=c(15,17), bty='n' )