A doughnut chart is the same as a pie chart, except for the “hole” that appears in the center.
Just as for a pie chart, if a data series is selected, a separate doughnut will be drawn for each category element and each doughnut will be comprised of the series elements. When a series is present, all the separate doughnuts are drawn on a single plot area and re-size in proportion with the plot. You have the option of stacking the different doughnuts or of drawing them in a line.
Data mapping for doughnut charts is exactly the same as for pie charts (discussed in section Section 5.8.1 - Data Mapping).