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.

- **Excel** 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.

- **Highcharts**, which is the charting engine we use, leaves the positive slices intact, but renders the negatives in a very odd and confusing way ([Example on JS Lint](http://jsfiddle.net/E4jg7/)). Props to them for trying to render negatives, but our users are confused.

- Others have suggested **filtering out the negatives** 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.

- And, others have suggested **using a more appropriate chart type**, such as a bar chart.

Any other options for solving this? How have you done it?