14 Jul 2016

Tableau Tips: How to Build a Donut Chart

Oscar Della Casa

The donut chart is simply an "evolution" of the pie chart, which is useful to represent data in the form of percentages of total - very helpful for visualising statistics.

We can create a donut chart by taking advantage of the dual axis option in Tableau. This function, in general, opens up numerous combinations of different chart types.

Building a donut chart mainly consists in overlaying a circle to a pie chart. The advantage of this kind of graph is the capability to include additional information about the underlying data. In the example below, the label in the middle shows the total sample population and the different colour sections describe de various deceases that affect them.

Donut Chart Tableau

FIGURE 1

The trick to building one of these is to create a new calculated field with value 0, as that will position the donut on the origin.

Figure 2

Move the field SUM(Donut) to the "Columns" twice, right click on one of the fields and tick the "Dual Axis" option. This will overlay the two fields on the origin.

Dual Axis Tableau

figure 3

From this point, it is possible to choose the marker type for each SUM(Donut) field in the marks window. The donut chart will be created by setting the two fields to "pie" and "circle" markers type respectively. I suggest changing the colour of the inner circle to make the size-adjustment process easier. All you have to do now is adapt the sizes of the two charts to reproduce something similar to the figure below.

Donut Chart Tableau

Figure 4

In my dashboard, I make use of donut charts to investigate how various diseases affect men and women throughout their lifetime.

The fatality of the different diseases seems to be quite similar for males and females for most of their lives. The situation gets more interesting in the 85+ age range. Here diseases of the circulatory system have much more incidence in men than women which, on the other hand, are more widely affected by dementia and Alzheimer's. You can actively investigate how the percentages change over different age ranges using the filter in the middle.

Check out our blogs for more tips and tricks to create interesting dashboards in Tableau!

Data Source: Cardiovascular Disease Statistics 2014, British Heart Foundation Centre on Population Approaches for Non‑Communicable Disease Prevention

 

Oscar Della Casa

About the author

Oscar Della Casa is a Graduate Analytics Consultant at Concentra. He studied Physics with Nuclear Astrophysics at the University of Surrey, followed by a master's in Financial Mathematics in Sydney, Australia. Oscar enjoys investigating data in all forms, using his scientific background to create unique and engaging visualisations.

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