Group by - Mode of categorical variable is sometimes completely off

[wvdvegte]

What's wrong?
When grouping by a categorical variable, selecting mode of another categorical variable sometimes produces an incorrect value

How can we reproduce the problem?
In the attached worfkflow, the variable "group" is grouped by cluster (apologies for the confusing variable name). In the result, for instance, the grouping of C2 shows in the concatenation that the DOS is the most occurring group, but the mode column shows HCD, which isn't even present in C2.
Group by - mode bug.zip

What's your environment?

• Operating system: Mac OS Sequoia
• Orange version: 3.38.0
• How you installed Orange: upgraded from DMG

[janezd]

This could be caused by #6906.

[janezd]

Note: The bug occurs in released Orange, which packages pandas 1.5.3. It seems that it cannot be reproduced with newer pandas, e.g. 2.2.3.