画一个“画”；箭头“；在R图的图例中

我在R图中有一条“曲线”和一个垂直定位的“箭头”（参见下面的R代码）

我想知道是否可以在“图例”中显示一个实际箭头，而不是一条平滑的直线来区分我的箭头和曲线？

这是我的R代码：

curve(dnorm(x), -4, 4, lwd = 3)

arrows(2, 0, 2, .3, code = 2, lwd = 3, col = 'red4')

legend("topleft", legend = c("Curve", "Arrow"), lwd = 3, col = c(1, "red4"))

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下面介绍如何在图例中用右箭头代替直线。您必须使用

par

访问font=5才能获得箭头符号

curve(dnorm(x), -4, 4, lwd = 3)
arrows(2, 0, 2, .3, code = 2, lwd = 3, col = 'red4')
legend("topleft", legend = c("Curve", "Arrow"), pch = c(NA, NA),
       lwd = 3, col = c(1, "red4"),
       lty = c(1, NA)) #normal legend. Do not plot line
par(font = 5) #change font to get arrows
legend("topleft", legend = c(NA, NA), pch = c(NA, 174),
       lwd = 3, col = c(1, "red4"),
       lty = c(1, NA), bty = "n") 
par(font = 1) #back to default

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类似的方法可能会奏效

windows(width = 6, height = 6)
curve(dnorm(x), -4, 4, lwd = 3)
arrows(2, 0, 2, .3, code = 2, lwd = 3, col = 'red4')

#Get the co-oridnates of extremes
extremes = par("usr")

#Determine how 'long' the lines should be in legend
xx = (extremes[2] - extremes[1])/16 #Change as necessary
yy = (extremes[4] - extremes[3])/16 #Change as necessary

#Draw lines and arrows
lines(x = c(extremes[1]+xx, extremes[1]+2*xx),
    y = c(extremes[4]-yy, extremes[4]-yy),
    lwd = 3)

arrows(x0 = extremes[1]+xx, x1 = extremes[1]+2*xx,
    y0 = extremes[4]-2*yy, y1 = extremes[4]-2*yy,
    code = 2,
    lwd = 3,
    col = 'red4')

#Labels for legend
lab = c("Line", "Arrow")

#Write labels in legend
text(x = c(extremes[1]+2*xx,extremes[1]+2*xx),
    y = c(extremes[4]-yy, extremes[4]-2*yy),
    labels = lab,
    pos = 4)

#Maximum string width of labels
bx = max(strwidth(lab))*1.5

#Draw polygon
polygon(x = c(extremes[1], extremes[1]+2*xx+bx, extremes[1]+2*xx+bx, extremes[1]),
    y = c(extremes[4], extremes[4], extremes[4]-(length(lab)+1)*yy, extremes[4]-(length(lab)+1)*yy))

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提示

font=5

将文本的其余部分更改为希腊字符，因此确实需要将其拆分为两个

legend

调用