Explain the problem as you see it
Currently, when using the "group by" view option on a field that has multiple values across the nodes being grouped, each individual value will get a group. While this is fine in some cases, it becomes impractical when a large number of values are possible groups.
Here's an example:
We have three nodes that are grouped by "example field." It would be great if there was a way to group nodes 2 and 3 together to the exclusion of node 1
Why is this a problem for you?
It becomes very hard to effectively group nodes and use the group by menu when there are a large number of values. And it could be useful to exclude nodes that have a definition.
Suggest a solution
Add a "is defined" option to the group by options.