title: Change the symbol in a legend key in ggplot2
body: <p>This R code produces a ggplot2 graph in which the legend key contains the letter "a" repeated in red, blue and green.</p>
  
  <pre><code>x &lt;- rnorm(9); y &lt;- rnorm(9); s &lt;- rep(c("F","G","K"), each = 3)
  df &lt;- data.frame(x, y, s)
  
  require(ggplot2)
  ggplot(df, aes(x = x, y = y, col = s, label = s)) + 
  geom_text() +
  scale_colour_discrete(name = "My name", breaks = c("F","K","G"), labels = c("Fbig","Kbig","Gbig")) 
  </code></pre>
  
  <p>I would like to replace the repeated "a" in the legend key with "F", "K" and "G".</p>
  
  <p>Is this possible please?  Thank you.</p>