Area-proportional pie chart highlighting in PowerBI

Question

It occurred to me that PowerBI's default behavior has pretty awkward highlighting (from ad hoc filters) in pie charts: it reduces the radius of the highlighted area proportionally, instead of the area.

Here's an example dataset:

Year;  Item;     Total
2016;  Apples;   50
2016;  Oranges;  100
2016;  Bananas;  200
2017;  Apples;   50
2017;  Oranges;  100
2017;  Bananas;  200

Visualized in two pie charts, with year 2017 highlighted by clicking on it in the right chart:

Now the radius of the inner circle is 1/2 of the full radius, but that means the area of the inner circle is a lot less than 1/2 of the the outer circle's area.

Is there a way to have the built-in PowerBI pie chart visual show highlights in an area-proportional manner?

Answer 1

You highlight a good point about the design of cross-filtering & pie charts in Power BI, especially since the radii aren't usually what people key in on to compare pie segments to each other*.

The simple answer is: no, you cannot change the built-in Power BI visual to show highlights (cross-filter), in an area-proportional manner.

There are, however, a few alternatives I'd like to suggest:

1. Use the built-in donut visual.

This suffers from the same flaw as the pie chart (that cross-filtering is done by radial length rather than by area). However, the inside 50% of a donut isn't quite as dramatically different area-wise as the outside 50% (compared to a pie chart). This is a quick & dirty alternative if a circular visual is important, and you want to remove as much of the distortion as you can (while not being perfect).

2. Use the built-in tree map visual.

This isn't a pie chart, but the square based segments allow for more accurate area-based highlighting.

3. Use a 100% Stacked Bar/Column Chart

These, again, aren't pie charts, but they do make it easier to see exactly how much of each segment is represented by the highlight (as well as to compare segments to each other). While not as glamorous as pies or trees, subtleties such as 48% vs. 52% would be starker. If the goal is to compare a selected year with the totals, I'd recommend this over a pie chart, even if a pie chart could highlight by area.

4. Change how the visuals interact with each other.

If your goal is primarily to see the breakdown of fruit in 2016 (rather than seeing how 2016 numbers contribute to the total), then changing a chart to filter instead of to highlight is recommended. Note, with your sample data, the proportions of 2016 are identical to the overall proportions. However, where proportions are different for different years, or where you have lots of years to the extent that any single year isn't that significant a portion of the total, this is a very good option.

To change from highlighting to cross-filtering:

1. Click on the chart you are clicking on to highlight other charts (the right-hand chart above)
2. Select Format > Edit Interactions on the ribbon
3. While still clicked on the first chart, click on the little Filter icon that appears above the chart you wish to filter instead of highlight.

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I know the above options aren't a way to accomplish what you'd like to do in the way you'd like to do it. One option, generally, when Power BI doesn't do something you expect is to submit an idea (or vote for an existing idea) at their ideas forum: https://ideas.powerbi.com/

Another option is to write your own custom visual or hire someone else to do so. This is likely overkill for what you want to do, but more information here: https://powerbi.microsoft.com/en-us/custom-visuals/

* Side-note: There's a good discussion about how pie charts are interpreted here: https://eagereyes.org/blog/2016/an-illustrated-tour-of-the-pie-chart-study-results