donutdiagram

A donut diagram, also called a donut chart or ring chart, is a circular statistical graphic that displays parts of a whole as segments of a ring. It is a variant of the pie chart with a hollow center. Each segment's angle and arc length are proportional to the value it represents, and the sum of all segments equals 100% of the dataset. The central hole can be left blank or used to show a label, total value, or a subcategory.

Construction and interpretation: The radius may be uniform for all segments; the inner radius determines the size of the hole, effectively creating a donut rather than a solid circle. Colors distinguish categories; labels or a legend provide the category names. Donut charts can be extended with multiple concentric rings to display hierarchical data or separate measures in the same visualization.

Usage and considerations: Donut charts are common for presenting a quick sense of proportion in business reports and dashboards. They are most effective with a small to moderate number of categories and when a central total is relevant. Comparisons across many segments or precise value reading are harder than with bar charts; the hole can reduce readability for small slices. Color choices and accessibility should be considered.

Software support: Donut diagrams are supported in many data visualization libraries and applications, including spreadsheets and programming environments. Typical controls include setting the inner radius or hole size, choosing colors, and adding central text. Nested donuts and multi-ring variants are used to show hierarchical data or additional series.