ggplot2：如何使用不同颜色的geom_vline（）

Question

我的情节中有五（5）个geom_vline（），我希望它们有不同的颜色。有没有办法做到这一点？

这是我的代码，

library(ggplot2)

x <- seq(-7, 8, length = 90)
tvalues <- dt(x,15)

qplot(x, tvalues) + geom_polygon(fill = "purple", colour = "purple", alpha = 0.5) + 
  geom_point(fill = "purple", colour = "purple", alpha = 0.2, pch = 21) +
  geom_vline(xintercept = c(a <- c(-2.27685371,  0.01661155,  
  0.33598194,  1.92426022), mean(a)), linetype = "dashed", colour = "red") + theme_bw() + xlab(bquote(bold('Average Tensile Strength (lb/in'^'2'*')'))) +
  ylab(expression(bold(P(x)))) +
  opts(title = expression(bold("Student t Distribution")), plot.title = theme_text(size = 20, colour = "darkblue"),
       panel.border = theme_rect(size = 2, colour = "red"))

这是输出，

注意图中的五条垂直线，我希望每条线都有不同的颜色，

我试过这个

library(colorRamps)
geom_vline(xintercept = c(a <- c(-2.27685371,  0.01661155,  
   0.33598194,  1.92426022), mean(a)), linetype = "dashed", colour = matlab.like(5)) 

但没有奏效，另一次尝试

geom_vline(xintercept = c(a <- c(-2.27685371,  0.01661155,  
   0.33598194,  1.92426022), mean(a)), linetype = "dashed", colour = c("red","blue","green","yellow","orange"))

仍然不成功。

提前致谢！

Answer 1

所以你有点想念 ggplot2 背后的基本理念，那就是你总是将所有数据都放到data.frame中，并且你绘制的每个美学对应一个变量你的数据框。

您可以获得5条垂直线，每条线都有不同的颜色，只有五次单独调用geom_vline，但是错过了整个包的重点。而是创建一个数据框：

a <- c(-2.27685371,0.01661155,0.33598194,1.92426022)
vlines <- data.frame(xint = c(a,mean(a)),grp = letters[1:5])

我已明确创建了一个分组变量grp以映射到colour。然后我们添加图层并使用aes：

将美学映射到这些变量

qplot(x, tvalues) + 
  geom_polygon(fill = "purple", colour = "purple", alpha = 0.5) + 
  geom_point(fill = "purple", colour = "purple", alpha = 0.2, pch = 21) +
  geom_vline(data = vlines,aes(xintercept = xint,colour = grp), linetype = "dashed") + 
  theme_bw() + 
  xlab(bquote(bold('Average Tensile Strength (lb/in'^'2'*')'))) +
  ylab(expression(bold(P(x)))) +
  opts(title = expression(bold("Student t Distribution")), 
       plot.title = theme_text(size = 20, colour = "darkblue"),
       panel.border = theme_rect(size = 2, colour = "red"))

（颜色很难区分，因为它们是虚线，其中两个几乎相互叠加。）

如果您从qplot过渡到ggplot()并开始将数据放入数据框而不是矢量，您将从 ggplot2 中获得更多。

Answer 2

如果您只想添加一行，添加以下geom会在x=1处添加红色的垂直线并以虚线显示。

+ geom_vline(aes(xintercept=1), colour="#BB0000", linetype="dashed")