Particle Flow Nth particle

Hi everyone sorry if this inst the right place to post, I have recently started using max and Particle flow and have got stuck on something that is probably quite simple but cant figure it out.

I have a flow with a data operator, inside the data operator I have a system that tests for number of particles within a given distance and if it falls below a certain number the condition is true and it is passed into the next event.

This works fine but obviously once the number of particles is bumped up it becomes very slow, so i have also filtered this by every nth particle which also works, the problem I have is although I want to filter the search by every nth particle i want to average that search across the original distance that I was searching for so the same amount of particles get passed into the next event as if the filter wasn't applied.

I hope that this makes sense. I have attached a pic to help make sense of what I am doing.

Thanks in advance for any help.