I’m trying to develop a way of removing List A from List B, such that the result is “any item in List B that does not have an equivalent in List A”. I have a feeling that current nodes out there find all equal values and remove them at once. If there are 4 values in List B “apples,apples,pears,pears” and 2 values in List B “apples,pears”, I want the output to be “apples,pears” - because two of those items are unaccounted for in the subtraction list. In other words, actual ‘count’ of item results is important, not just the values themselves.
Okay, so I have tried with recursion but I can’t get it working. See below for my current work:
Please help, thanks 
I got what I wanted in Python, I will publish eventually in Bakery package:
Have you tried the SetIntersection node?
I’m not too sure if this does what you want. But it is in Rhythm.
Luke,
My earlier response wasn’t what you were looking for, I realized.
I suppose the Design Script code I’ve attached below should do what you are trying to achieve. (“actual ‘count’ of item results is important, not just the values themselves”)
File: Remove InstancesFromList.dyn
@John - A similar result is obtained by using the SetDifference node
Vikram,
Thanks for your designscript example, it does work and gets a similar result to the Python version I showed above.
However, I cannot get it working in a custom node. I am running 0.8.0 and when I add the function to the custom node as per image below, Dynamo essentially just stalls ‘not responding’. Am I doing this wrong?
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Luke - Might have something to do with ‘from’ in your Input node.
Node file (created in Dynamo Studio, so the version is 0.8.0): RemoveList Instances.dyf
I had a problem with the login screen for a few days. Here’s another way that can get into nested lists…
