title: regression lines over subsets in ggplot2 boxplot
body: <p>I want to plot regression lines over two subsets of boxplots in ggplot. however it looks like it is not possible.</p>
  
  <p>Here is the <a href="https://www.dropbox.com/s/j4zarc5l4rriwey/uro7.csv?dl=0" rel="nofollow">dataframe</a></p>
  
  <p>Here is the code:</p>
  
  <pre><code>ggplot(VMT,aes(x=size , y=vmt, group=specimen,colour=sex,fill=sex)) +
  geom_boxplot()+
  scale_colour_brewer(palette="Set1")+
  #geom_point()+
  ylab("VTM (°C)")+
  xlab("size")+
  geom_smooth(data=subset(VMT,sex==F),
            aes(mean(size),mean(vmt),      group=specimen,color=sex,method=lm,se=FALSE))
  </code></pre>