title: Combined bar plot and points in ggplot2
body: <p>I would like to plot a "combined" bar plot with points. 
  Consider to following dummy data:</p>
  
  <pre><code>library(ggplot2)
  library(gridExtra)
  library(dplyr)
  
  se &lt;- function(x){sd(x)/sqrt(length(x))}
  
  p1 &lt;- ggplot(mtcars, aes(y=disp, x=cyl, fill=cyl)) 
  p1 &lt;- p1 + geom_point() + theme_classic() + ylim(c(0,500))
  
  my_dat &lt;- summarise(group_by(mtcars, cyl), my_mean=mean(disp),my_se=se(disp))
  
  p2 &lt;- ggplot(my_dat, aes(y=my_mean,x=cyl,ymin=my_mean-my_se,ymax=my_mean+my_se))
  p2 &lt;- p2 + geom_bar(stat="identity",width=0.75) +     geom_errorbar(stat="identity",width=0.75) + theme_classic() + ylim(c(0,500))
  </code></pre>
  
  <p>The final plot should look like that:
  <img src="https://i.stack.imgur.com/MTsFX.png" alt="example plot"></p>