Question about the Logic of Lists

Hi All,

In the following exercise I am trying to cull all the surface perimeter curves that are at the top of the z axis…

I don’t quite understand why the List.MaximumItem node flattens out a branch. I have used the “Use Levels” to get the list structure back to it’s initial format that was created with the Surface.PerimeterCurves … but now cannot figure out how to get the IndexOf to share the same structure without doing some sort of list manipulation at the end. Is there any simple way of carrying the structure of the tree all the way through so that I can retrieve the curves that I want?


If I’m understanding what you’re asking, I think you can set List.GetItemAtIndex to Use Levels and set it to @L2. This will look at the second level of your Surface.Perimeter Curves and apply those values to find the items at those indices. Let me know if that works.

@nathaniel.g.macdonal thanks for the response!.. Well what you suggested helped me to resolve the problem… I had to set the “list” @L2 and the “index” @L1… Which starts to make sense now that I think of it.

I thought I had to match the list structure on each to get the correct output… but that wasn’t the case either

When I “use levels” with the graph above though, it works… still a little confused there, but I got what I need now and seem to have the basic understanding of how the first graph pictured is working


Yup, you don’t necessarily need to have the same list structure but make sure you are applying the index list to the correct sublist. If that answer solved your issue, feel free to mark it as so with the checkmark icon, so future readers can see it.