使用表达式的替代方法是Unicode字符，在这种情况下，Unicode字符'大于或等于'（U + 2265）。复制@ mnel的例子

  .d<  -  data.frame（a = letters [1：6]，y = 1： 6）

 ggplot（.d，aes（x = a，y = y））+ geom_point（）+ 
 scale_x_discrete（labels = c（letters [1：5] \\ u2265 80））
 

如果您无法记住复杂的表达式语法，如果你需要换行符，哪些表达式不允许。作为缺点，特定的Unicode字符是否完全取决于您的图形设备和选择的字体。

I have a plot which is generated thus:

ggplot(dt.2, aes(x=AgeGroup, y=Prevalence)) + 
    geom_errorbar(aes(ymin=lower, ymax=upper), colour="black", width=.2) +
    geom_point(size=2, colour="Red")

I control the x axis labels like this:

scale_x_discrete(labels=c("0-29","30-49","50-64","65-79",">80","All")) +

This works but I need to change the ">80" label to "≥80".

However "≥80" is displayed as "=80".

How can I display the greater than or equal sign ?

An alternative to using expressions is Unicode characters, in this case Unicode Character 'GREATER-THAN OR EQUAL TO' (U+2265). Copying @mnel's example

.d <- data.frame(a = letters[1:6], y = 1:6)

ggplot(.d, aes(x=a,y=y)) + geom_point() + 
    scale_x_discrete(labels = c(letters[1:5], "\u2265 80"))

Unicode is a good alternative if you have trouble remembering the complicated expression syntax or if you need linebreaks, which expressions don't allow. As a downside, whether specific Unicode characters work at all depends on your graphics device and font of choice.