Compare two list and use 3rd list to fill in 4th based on what is in the other list

I have two lists I have made out of Revit With Dynamo.
one is a list that was taking from Piping systems with a custom parameter that has what pipe type use be used for the system.
the second list is a list make from pipes and has a custom parameter that has what the required system is,
i want to search on the list from the systems and compare it to the systems showing the required systems and then write the parameter from the system list to the pipe parameter. i hope i am making sense

I’m a little confused on what you’re trying to do here. What is your end goal? Are you trying to convert all pipe systems to the correct pipe type?

The end goal is to take the info from the piping systems that are set and write that parameter to a pipe Parameters. i want to be able to use the pipe schedule to show the piping that is on the wrong system

So your Pipe Systems have a parameter for the specified Pipe Type and your Pipes have a parameter for the specified System Type. That part I’m pretty sure I follow.

But I’m still a little cloudy on what you’re trying to do with that information. You want to write the Pipe System parameter value to all Pipes of that System Type so that you can use a schedule to compare the “Actual Pipe Type” to the “Specified Pipe Type”? Is that it?

not really sure how else to explain it.
the first two are from the systems parameters

the next two are from the piping

i want to compare the top one to the bottom one in this picture

and then take the info from the copy the parameter from the Pipe system Parameter “Pipe System Pipe Type” to the Pipe parameter “System Pipe Type Required”
i hope that helps because i am not sure how else to explain it

I think you’re making this more complicated than it needs to be.

Take your list of Pipes and get the parameter value for “System Type”. This will return the actual Pipe System. You can then get the “Pipe System Pipe Type” from the system and write that information to the Pipe’s “System Pipe Type Required” parameter.

No need to get everything beforehand and compare.

the pipe needs to look for the system and then return that valve and i don’t know if there is a shortcut to getting to that

If the parameters are assigned to the Pipe System Types you can get the System Type (and therefore their parameter values) from the Pipe element. If they’re assigned to the actual Pipe System you’ll need to use the custom node from MEPover.

there are over 250 piping systems in the project I am trying to make a fail-safe so people are not using the wrong pipe and systems for each system. I really can’t explain what I am trying to do. but if I can compare the list and copy the one parameter to the other parameter it will work the way i need to too is isn’t just system type

Can you show were these parameters are coming from then? What elements are you using for the input?

This should work for you then. Rather than getting the System information from a list of Systems get it directly from the Pipe element. Use the workflow I’ve shown and see where that gets you.

i am not getting it a cross,
the key is to take the info that is typed into the piping systems and make sure that when people model piping they are using the right pipe for the system. i can’t get all that info from the pipe

You won’t be able to force them to use the correct pipe but you can use a schedule to show which pipe is using the incorrect type, like you mentioned earlier.

that is what i am trying to do

Is this what you’re trying to do?

that seem to have worked