title: How do I plot the mean instead of the median with geom_boxplot?
body: <p>for some inane reason, I need to create a boxplot where the middle line is the <strong>mean</strong> instead of the median. I checked stackoverflow already and found examples of <em>adding</em> a mean line, but not exactly what I need. I tried using stat_smooth but no dice. Any ideas?</p>
  
  <p><em>code below:</em></p>
  
  <pre><code>dust &lt;- c(4.5, 3.7, 5, 5.2, 8.5, 6.6, 4.7, 5, 5.7, 4.3, 2.3, 7.6, 5.2, 
            6, 8.7, 7.5, 7.7, 11, 9, 6.5, 8.7, 5, 2.2, 7.5, 7.5, 3.5)
  
  wind &lt;- c("Present", "Absent", "Absent", "Absent", "Absent", "Absent", 
    "Absent", "Absent", "Absent", "Present", "Absent", "Absent", 
    "Present", "Present", "Absent", "Absent", "Absent", "Absent", 
    "Absent", "Present", "Absent", "Present", "Absent", "Absent", 
    "Absent", "Present")
  
  df &lt;- data.frame(dust,wind)
  
  plot &lt;- ggplot(data=df,aes(x=wind,y=dust))+geom_boxplot()+stat_smooth()
  
  plot
  </code></pre>