Help - Give elements sequential numbers with identical elements getting the same number?

I want to give each pipe fitting a sequential number starting 14/ but only those with the material parameter “Ductile Iron”. The filter and numbering works in isolation but cant seem to get dynamo to give identical items the same number?

Any advice apprecitated…
PF Numbering.dyn (65.9 KB)

You’ll need to take another screenshot that’s legible but you should be able to group by key to group identical items and then number based on unique keys instead of unique items.

Hi @Nick_Boyts

Thanks for the reply, hopefull this is legible now, can you elaborate pls?