Group and count in list

Revit
1

Hi guys,
im trying to merge (or combine ? or map ? ) lists (for simple grouping and then counting elements), but im not sure if it is possible to create list exactly like this (see attachm.):

img01
img01945×1149 56 KB

(Count.Occurences in pic is from Clockwork package)

So much thanks for any help
Martin

2

Option using List.IndexOf and ListGetItemAtIndex

image
image2958×1210 228 KB

Hope this helps,
Thomas

42850.dyn (7.9 KB)

3

Thank you Thomas!! This is exactly what I was looking for