Workflow to select only elements on a list that share the same value of a parameter

Good afternoon to everyone, as the title says i have a list of elements (in this case, windows), and then i have a list of values of the parameter called “Cod_oggetto”; every item under the sublist has to own a unique value of this parameter, so i modified the value of one window from 19 to 20, so that right now i have two value “20” on the list. Is there a way to create an output where i have on a list all the elements (in this case just two) that DON’T HAVE a unique value of the parameter? Thanks in advance.

Hi @umberto95 ,

If I understood what you’ve been trying to accomplish, you can do as shown in the image. This is an example using beams, so apply it in your case and see if that’s what you’re looking for.

Thanks for the help! The idea is perfect, but i forgot to mention the fact that my list of windows is organized in sublists based on levels, because every window on the same level should have a unique value of that parameter, after playing a bit with levels i do obtain the two windows with the same value of the parameter, characterized by index 18 and 19, but also i obtain the windows with the indexes 18 and 19 on the other levels, do you have any idea on how to solve this?

I tried so simulate your case. Try this and check if this can solve the problem.

I really appreciate your effort

, but as you can see in the picture the output says null without any reason.

Try to change the lacing to “auto” like in the picture I’ve attached.

Maybe i’m using an older version of Dynamo (1.3), i only have shortest, longest and global; anyway, isn’t auto equal to shortest?
By the way, the last node “List.GetItemAtIndex” says the following error: Warning: Converting an array to int would cause the order of the array to be reduced and is not allowed.

Funny thing i discovered, i also had to apply this script to doors, which have unique values based not on the level, but on the room they are associated with. Without any sense the script works perfectly on those.

Maybe it can be the version as you said, but I confess that I don’t know about that scenario, because I started to used Dynamo about two months ago, so I don’t know the differences between the versions.
Now, what are the main differences between the structure lists related to the doors and windows? Can you attach a picture showing the doors list? It seems to be a problem related to the list structure.