如何在ggplot2图例标签中添加Latex代码？

Question

考虑以下示例：

p <- ggplot(data = data.frame(A=c(1,2,3,4,5,6,7,8),B=c(4,1,2,1,3,2,4,1),C=c("A","B","A","B","A","B","A","B")))
p <- p + geom_line(aes(x = A, y = B,color = C))

我想更改传奇中的标签来自＆＃34; A＆＃34;和＆＃34; B＆＃34;乳胶配方，说＆＃34; $ A ^ h_ {t-k} $＆＃34;和＆＃34; $ B ^ h_ {t-k} $＆＃34;分别。

显然，根据答案here，存在实现这一目标的方法。但是，我真的很难让它发挥作用。有人可以为我分解吗？

Answer 1

要使用真正的LaTeX语法，您可以使用latex2exp包。请注意使用unname()，这是必要的。

library(ggplot2)
library(latex2exp)
df <- data.frame(A = c(1,2,3,4,5,6,7,8),
                 B = c(4,1,2,1,3,2,4,1),
                 C = c("A","B","A","B","A","B","A","B")
)
ggplot(df) + 
  geom_line(aes(x = A, y = B,color = C)) +
  scale_color_discrete(labels = unname(TeX(c("$A_{t-k}^h", "$B_{t-k}^h"))))

由reprex package（v0.2.0）创建于2018-05-29。

Answer 2

library(ggplot2)
df <- data.frame(A = c(1,2,3,4,5,6,7,8),
                 B = c(4,1,2,1,3,2,4,1),
                 C = c("A","B","A","B","A","B","A","B")
                 )
ggplot(df) + 
    geom_line(aes(x = A, y = B,color = C)) +
    scale_color_discrete(labels = c(expression(A[t-k]^h), expression(B[t-k]^h)))