title: Keep grid lines and (optional) tick marks when using breaks ggplot
body: <p>I'm creating a line graph with ggplot that makes use of <code>breaks</code> to display only some of the labels. The issue is when I do that, the non-labeled tick marks and more importantly, the grid lines associated with those tick marks disappear. I really need the grid lines to remain. The tick marks staying would be nice, but not essential. </p>
  
  <p>The code below will produce a graph that shows what I'm dealing with.</p>
  
  <p>Thanks!</p>
  
  <pre><code>count&lt;-c(1,5,6,8,3)
  period&lt;-c(1,2,3,4,5)
  
  df&lt;-data.frame(count,period)
  
  library('ggplot2')
  ggplot(data=df, aes(x = period, y =count ,group=1)) +
    geom_line(size=1)+
    scale_x_discrete(breaks=c(1,3,5),
                     labels=c("One",'Two','Three'))
  </code></pre>