title: using plotmath symbol in ggplot2 geom_text - legend is altered - why?
body: <p>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?</p>
  
  <pre><code>d &lt;- 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)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/Tb2eN.png" alt=""></p>