Curtain Walls Orientation

Hi guys,
i’m trying to determinate the percentage of curtain walls length compared to total length of walls at every orientation and at every level (in particular, level 1 and 2). I used the component Wall.NorthSouthEastWest from Rhythm repository, but there is some issue according to nested lists. In the example above, for the east exposition, there is a curtain wall only at level 2, so for the east output component returns “empty list” for the first level and “wall ID” for the second one. The problem is that the two results are on differents list levels (@L3 “Empty list” and @L4 “Wall ID”).
How can i resolve this issue?

curtain walls.dyn (24.9 KB)

Here it is the revit model:

Thanks everyone

From its definition, the Wall.NorthSouthEastWest node is wall-agnostic - guess it should be renamed to group list item by taking XY vector components as keys or something.

So the fix is obvious but quite counter-intuitive - you just get the parameter value before, not after. Does it make sense to you?

Sorry for not working on your dynamo file - it was language or package issue. But you should get the rationale and be able to fix it yourself.