Organize flat list of Revit Elements into sublists based on parameter value

[Ewan_Opie]

You could try using the node similar to this. An oldie but a goody.

Group by key

The key projector is just a function that operates on the list to be sorted. Take, for example, a list of points, and I want to group them by they x-coordinate. [Capture] Also check out this thread: http://dynamobim.org/forums/search/group+by+key/, which uses an alternate technique in the case where the logic you are grouping items by is not directly related to the items themselves.

EDIT:

Here is a basic example of Mirror families hosted to walls. I have randomized the input list and you can see how the Group.ByKey node is grouping by the specified parameter, Element Id.