donut - easily create a donut char​t using pie syntax

Donut creates a donut chart with offset slices and custom labels.

The pie chart in Matlab could not be plotted in a donut style (with an area of the center cut out). This function creates a donut chart by changing patch vertices of the pie chart. Thus, it maintains all the syntax and editable properties (offsets slices and specifies the text labels) of pie function. It could be used to display proportions or cyclic colormaps.