Introduction
This week we are exploring a new type of visual: an Euler diagram.
An Euler diagram is a powerful visualization tool used to depict hierarchical relationships and set containment. Unlike a Venn diagram, which displays all possible logical intersections—even those that are empty—an Euler diagram focuses specifically on the connections present in your data. By using nested shapes to show subset-superset relationships, an Euler diagram provides a cleaner, more intuitive way to understand categorical hierarchies at a glance.
The example below was created in the Deneb custom visual using Vega, but you are welcome to create your diagram with any visual type available in Power BI. It’s likely this could be accomplished with the HTML in the HTML Content visual or a card visual, or a custom visual that creates Venn diagrams. I’d love to see your version if you choose to use something other than Vega! The original version of this visual seems to have been created by Sam Hughes in 2007. There is a modified version on Wikipedia from 2011, which is where I first encountered it.
Dataset
The dataset is the 3-column table shown below. You can copy and paste it directly into Power BI Desktop. You may want to enhance the dataset with additional columns to complete the challenge.
| name | level | parent |
|---|---|---|
| British Isles | 0 | |
| British Islands | 1 | British Isles |
| Ireland (island) | 1 | British Isles |
| United Kingdom | 2 | British Islands |
| Ireland (state) | 2 | Ireland (island) |
| Northern Ireland | 2 | Ireland (island) |
| Great Britain | 3 | United Kingdom |
| Jersey | 3 | British Islands |
| Isle of Man | 3 | British Islands |
| Guernsey | 3 | British Islands |
| Scotland | 4 | Great Britain |
| England | 4 | Great Britain |
| Wales | 4 | Great Britain |
Note: Data originally retrieved from Wikipedia (CC0) and formatted and reposted here for this exercise. If you disagree with the labels in the data, feel free to modify them. We want you to enjoy the data viz exercise.
Requirements
- Create an Euler diagram in your visual of choice. The visual must accurately represent the parent-child relationships defined in the dataset through proper circle nesting.
- Clearly show all overlapping border lines of the circles and ensure each circle is labeled.
- Use design elements (such as stroke weight, opacity, or color) to differentiate between parent and child containers.
Note: I implemented a relative positioning and scaling system in the dataset (by adding additional columns in Power BI), where each circle’s position and dimensions are calculated as fractions of their parent. This ensures that if the hierarchy or the root size changes, the entire diagram updates proportionally and automatically. You do not have to do this. If you want to hardcode the position of the circles, that still meets the requirements.
Share
After you finish your workout, share on BlueSky or LinkedIn using the hashtags #WOW2026 and #PowerBI, and tag @MMarie, @shan_gsd, @KerryKolosko (on BlueSky).