How does the group sorting work for categorical columns?

[thinkh]

I was discussing the group sorting the other day with a customer and we could not come up with a comprehensible explanation how the group sorting is working for categorical columns. Maybe you can help us here.

Steps to reproduce

1. Open https://lineup.js.org/develop/group3.html
2. Collapse by third aggregation level
3. Add sort groups by for Cat4

Observed behavior

Without group sorting (i.e., aggregation only) the pattern of the groups is clear and follows the group hierarchy.

However, once I sort the groups by Cat4 the pattern looks totally different. The groups do not follow the group hierarchy, but it is also not obvious that they are sorted by Cat4. There is a slight pattern that the groups are first sorted by d1 and then d2, but the sorting criteria itself is not obvious.

Question

@sgratzl Could you please explain how the groups are sorted in this example?

P.S. We discuss the group sorting also in PR #273 (review), but I did not sort the groups by a categorical column that is not used in the group hierarchy.

[sgratzl]

it is sorted by the most frequent category in the histogram of cat 4. In the upper half it is the blue ones in the lower ones it is the orange ones

[thinkh]

Thanks for the clarification. I close this issue for now and reopen it if necessary.