title: forcing ggplot2 y-axis label to be of integer only, and give proper breaks
body: <p>I am drawing barchart for discrete data and ggplot by default adjust the y-axis for me, but gives me y-axis label with breaks at 0.5 interval which I don't like it. I tried <code>scale_y_discrete</code> but y-axis breaks is given for every discrete value, which is not good also. </p>
  
  <p>Can I force the y-axis break to be composed of integer only, and give proper breaks for each of the facet?</p>
  
  <p>Sample script is as below:</p>
  
  <pre><code>set.seed(1)
  chart.data &lt;- data.frame(x=rep(LETTERS[1:10],3),
                           y=c(sample(0:10,10,replace=TRUE),
                               sample(0:100,10,replace=TRUE),
                               sample(0:1000,10,replace=TRUE)),
                           group=sort(rep(1:3,10)))
  chart &lt;- ggplot(data=chart.data,aes(x=x,y=y))
  chart &lt;- chart + geom_bar(stat="identity")
  chart &lt;- chart + scale_y_discrete()
  chart &lt;- chart + facet_wrap(facets=~group,nrow=1,scale="free_y")
  </code></pre>
  
  <h3>Update #1</h3>
  
  <p>Since the post is being considered as possible duplicate, the script is refined to show a more complicated scenario.</p>