title: Negative values in pie charts
body: <p>My application visualizes data using a variety of chart types. Some data visualized by a pie chart includes negative values. Pie charts aren't designed to display negatives.</p>
  
  <p><li><strong>Excel</strong> outputs the absolute value of all values. So, -20 is output in the pie chart as a slice with 20% of the pie's circumference. The only way to tell the number is negative is to reference the legend.</li></p>
  
  <p><li><strong>Highcharts</strong>, which is the charting engine we use, leaves the positive slices intact, but renders the negatives in a very odd and confusing way (<a href="http://jsfiddle.net/E4jg7/" rel="nofollow">Example on JS Lint</a>). Props to them for trying to render negatives, but our users are confused.</p>
  
  <p><li>Others have suggested <strong>filtering out the negatives</strong> altogether, since they don't make sense on a pie chart. This strips data and doesn't wholly represent the data set, so it probably won't work for us.</li></p>
  
  <p><li>And, others have suggested <strong>using a more appropriate chart type</strong>, such as a bar chart.</li></p>
  
  <p>Any other options for solving this? How have you done it?</p>