Question

I want to position a plotmath symbol (x bar) in a plot using ggplot2. Somehow the way I do it alters the legend. The letter “a” suddenly appears. Where do I go wrong here?

d <- data.frame(x=rnorm(10), y=rnorm(10), g=rep(c("m", "w"), 5))
ggplot(d, aes(x, y, group=g, color=g)) + geom_point() +
    geom_text(x=0, y=0, label="bar(x)", parse=T)

Answer 1

This will fix the problem:

ggplot(d, aes(x, y, group = g)) +   
  geom_point(aes(colour = g)) + 
  geom_text(x = 0, y = 0, label = "bar(x)", parse=T)

Only add colour the points.

Or, if you want to annotate the plot, annotations will not be placed in the legend so

ggplot(d, aes(x, y, group = g,colour = g)) +   
  geom_point() + 
  annotate('text',x = 0, y = 0, label = "bar(x)", parse=T)

would work.