title: How to add data labels using axlsx
body: <p>I'm trying to generate a pie chart using axlsx for ruby.  Everything is working fine but I can't seem to get data labels to appear for each "pie slice".  What I'm shooting for is more or less like this <a href="http://www.nwscc.edu/nsfdc/troberson/excel.7.jpg" rel="nofollow">image</a>.  (ie it should have the data labels and leader lines).  It would also be fine to have the labels just have the numerical value and include a legend with the color mapping as usual.</p>
  
  <p>Anyone know how to do this?</p>
  
  <p>Thanks</p>