Sunburst chart, known by multiple names such as ring chart and radial treemap, is used to visualize a hierarchical dataset.

It shows hierarchy through a series of concentric rings, where each ring corresponds to a level in the hierarchy. Each ring is segmented proportionally to represent its constituent details. Focussing on a segment in the ring gives a sense of the part to the whole relationship of the segment with respect to its parent ring segment.

A Sunburst chart uses a radial layout to create an immersive visualisation experience of the categorised dataset. It is a space-filling visualization that uses a radial, rather than a rectangular layout (like a Treemap) The Sunburst chart is very effective to showcase how one ring is broken into its contributing pieces (i.e, sequential segments).

Components of a Sunburst Chart

The rings in a sunburst chart are divided based on their hierarchical relationship to the parent node. Each ring can have multiple segments; each segment showing the contribution of a particular dimension in that hierarchy. Focussing on a segment in the ring gives a sense of the part to the whole relationship of this dimension with respect to its parent ring segment. The slices in a sunburst chart may be coloured to highlight hierarchy or category.

A simple sunburst chart illustrating the events in the league stages of FIFA 2018.

Sunburst chart showing the population of different regions in 2017

If you’re looking for a chart other than Sunburst to represent hierarchical data, you may choose among these alternatives to the Sunburst chart.

Treemap vs Sunburst chart

In a treemap, as we go down the hierarchical levels, the space available to plot decrease dramatically. This sets a limitation to the number of hierarchical levels that can be displayed at once. As the categories delve deeper, they become harder to read. This is good for comparing macro-level data and giving viewers a sense of how many sub-categories there are. But it isn’t really effective when you want to drill down into those sub categories.

However, in a Sunburst chart, it’s exactly the opposite! The more we go down the hierarchical levels (creating/plotting new levels in the chart), the more space we get. When space isn’t really an issue, choosing a Sunburst chart is a good idea to paint a full picture of the multiple layers of data among the hierarchical groups.

Multi-level Pie chart vs Sunburst chart

The multi-level pie chart is a special type of chart that allows you to show symmetrical and asymmetrical tree structures in a consolidated pie-like structure. It presents the entire hierarchical data in a single-screen snapshot, which makes it a preferred choice over a tree view. Sunburst charts shows the hierarchy of the categories, thereby giving a very clear understanding of the lineage.

Use cases of the Sunburst Chart

  • Outlining the landing and navigation paths of a website
  • Visualising file size of different modules in a software package
  • Understanding the revenue sources of a business
  • World population broken down into a particular continent, country, region, state, city, town
  • Salary expenses of employees across departments in an organisation

Advantages and Disadvantages of the Sunburst Chart

  • The radial orientation of the sunburst chart utilizes space more efficiently compared to the linear (horizontal or vertical) hierarchical visualization. All elements on the same level are regarded equally important, thereby eliminating the dichotomy between the elements on the periphery and center.
  • Since it resembles a pie chart, which most of us are familiar with; the Sunburst chart is intuitive in nature.
  • The radial structure limits the number of nested levels that can be easily understood from a static picture.
  • Understanding angular readings is difficult for human eye.