Ben House

If there is no name or other identifying attribute, a simple way to group identical objects is to group them by point or primitive number as you described. It won't always be perfect though. One way to do this is to loop through each connected piece and create a group named after the number of points, such as putting group`npoints(opinputpath(“.”,0))` in the Group Name parameter. Make sure your Initial Merge is set to Union with Existing. File attached.

If you want something more exact to the shape/silhouette, then you could probably compare point positions per piece using an attribute wrangle and group them that way? It would be a lot slower, but would be much less error prone.

I'm sure there's a more elegant way to do this, but if it's always going to be a flat plane, the first thing that comes to mind is that you can use PolyExpand2D and PolyExtrude to create a volume from your original outline and use that to group the points along the outer edge. Then convert that point group to edges with only the fully contained elements to get your outer edge group. Lastly, use a GroupCombine to group all edges but your border edges. This should at least let you keep moving forward for now.

I think you might be looking for the Attribute Blur [www.sidefx.com] node?