Pie Chart Usage and Data Format
You can use the Pie Chart widget to
visualize results of the groupBy() and
top() functions.
If you need to display multiple aggregate results in a single chart, you
may prefer the Bar Chart widget,
typically used to display multiple aggregate results.
As an alternative to bar charts, the Pie
Chart supports the
small multiples option to
visualize multiple aggregate results, see
Method Distribution in Small Multiples for an example.