Hi,
I have a list of selected “Beams” elements in Dynamo.
What’s the best way to identify “Beams” that are exactly the same (geometric)?
I’m new to Dynamo, I need to give a number (Mark) for each beam, but the same beams must have the same number.
Thank you very much! 
Below is an image of my structure to get an idea of how the beams are.
List.GroupByKey should get you somewhere. What have you tried so far?
I’m new to Dynamo. But initially I thought of using the “Centroid” of the beams to identify the same beams, but the centroid points are based on the 0,0 of the project, so they don’t match. So I managed to get the list of beams volumes. How do I compare equal volumes in the list and give a number to each group of equal parts?
Once you have the volume, you use that as they key input, and the beam elements as the list input of anList.GroupByKey node.
However if you have three rectangular profile beams with the following dimensions they’ll all have the same volume:
Rather than using volume, use the beam type and the beam length.
Right!
But to better understand how it works, how could I evaluate and order a list based on two or more factors? (in a list compare elements of the same “type”, same “volume” and same “length”, for example).
GroupByKey repeatedly using list levels.
Or union the comparison values into a single string and use that as the key.
