The short answer is, you probably shouldn't.
It is just a bad idea to go through a series of potentially hundreds of particles per particle generated.
In my case, I just wanted to know how to set it up (if possible). I want to sample a total of 5 (non-loop) particles for a film and I am the one controlling the amount generated so that cost is not a risk factor for me.
You build your algorithm to use nSamples per particle and use that short sample to guess the real value. This makes your algorithm inaccurate, but potentially fast enough to be viable in the game.
Sorry, I'm not sure if I'm following that algorithm? I'm just looking for something to put in my "Particle Index" so that I can sample 5 particles at a time instead of 1 at a time. Is that possible?
You precompute values for your set of particles outside of the particle execution phases (BP in the case of unreal). However, this only really works if the values you need for the particles are consistent across all particles.
I feel very slow today. What values are you referring to? All I need is a way that the input “Particle Index” includes my total amount of particles produced. Again if possible.