Consolidate List Elements

I recently posted an issue regarding the Steamworks Tool.GetSurroundingElements. The Tool was not working for locating light fixtures when the rooms are in a linked model. In any case I have abandoned that method and have been successful in creating bounding boxes and locating the fixtures by coordinates. I have finally produced a list represented by the concept attached. I would like to group the resulting list by the number with each associated letter. So from the attachment, the result would be 0,a,b,c then 1,d then 2,e then 3,f. Can someone help with this?

Try this:

Thanks Thomas. Definitely a step in the right direction. I now have two lists with the groups being the light fixtures and the unique keys being the room numbers. So I have the correct number and types of fixtures in the correct location in the list for the room associated. Now I will get some parameter data (load, voltage, etc) and dump it all in a spreadsheet for analysis.

This solved the problem and results in the list arrangement needed.