title: Customize Contour Labels in ggplot2
body: <p>I'm relatively new to ggplot2, and I'm having trouble adding appropriate labels to my contours. I would love to be able to add the labels without the directlabels package, but I haven't found a way to, so if you know of a way to customize labels without directlabels, I would love to here it.</p>
  
  <p>Using the classic volcano example, I can add labels to the default contour plot using the directlabels packet in the following way:</p>
  
  <pre><code>library(plyr)
  library(ggplot2)
  library(directlabels)
  library(reshape)
  volcano&lt;-melt(volcano)
  v&lt;-ggplot(volcano, aes(x,y,z=z))
  e&lt;-v + stat_contour(aes(colour=..level..))
  direct.label(e)
  </code></pre>
  
  <p>In the above example, the labels are added appropriately, but things become more complicated if I try to specify my own break points for the contours:</p>
  
  <pre><code>e&lt;-v + stat_contour(aes(breaks=c(160, 170, 180), colour=..level..))
  direct.label(e)
  </code></pre>
  
  <p>Now, the contours are specified by the breaks I have provided, but labels still appear for all of the default contours. How do I only plot only labels for the graphed contours?</p>
  
  <p>A related issue, how would I plot labels for contour levels not included in the default? Say a break of 165:</p>
  
  <pre><code>e&lt;-v + stat_contour(aes(breaks=c(165), colour=..level..))
  direct.label(e)
  </code></pre>
  
  <p>Thanks for any help!</p>