r - ggplot 中的希腊字母注释

Question

我想将希腊字母添加到 ggplot 中的文本中。这是我想做的:

library(ggplot2)
df <- data.frame(x =  rnorm(10), y = rnorm(10))
xIntercept <- mean(df$x)
yIntercept <- mean(df$y)
temp <- paste("theta = ", xIntercept) # This Works
ggplot(df, aes(x = x, y = y)) + geom_point() +
  annotate("text", x = xIntercept, y = yIntercept, label = temp, color = "blue")

我想使用希腊字母 theta，而不是“theta”。我试过这个link但做不到。我尝试了以下代码，但什么也没发生:

temp <- list(bquote(theta == .(xIntercept)))
temp <- bquote(theta == .(xIntercept))
temp <- expression(theta, "=", xIntercept)
temp <- c(expression(theta), paste0("=", xIntercept))

Answer 1

您的链接指出，在 annotate 中，您应该使用 parse = TRUE。所以

ggplot(df, aes(x = x, y = y)) + geom_point() +
  annotate("text", x = xIntercept, y = yIntercept, label = temp, color = "blue", parse = TRUE)

有效并给出希腊西塔符号。编辑:但是 = 符号也被解析，所以 MrFlick注意到你应该去

temp <- paste("theta == ", xIntercept)