So there are two different ways you can filter for this content. The first is using the Group By component which will group all of the objects together using a specific attribute or user text as the sorting criteria. So, that would simply look like this image below. You can then select the items in the tree that you’re interested in.
The second way would be to filter the objects by a specific filter. In this case, I’m using the Match Text filter to select only the objects whose display colour matches 255,0,0 (ie. red). That would look like this.
Here are the files in case you’re interested.
Circles.3dm (76.2 KB)
FilterByColour.gh (11.7 KB)