How can I set pre-existing targets in MultiTargetGroundTruthSimulator?

[ekhunter123]

The scenarios I'm trying to simulate often involve several targets which exist from the very beginning of the simulation. For example, there could be 5 targets moving around with 0 births and 0 deaths. But the MultiTargetGroundTruthSimulator has the line

groundtruth_paths = set()

in the first iteration of the groundtruth_paths_gen() function. What is the best way to get those targets to exist from the very beginning? It would be nice if I could even provide my own starting states for those targets.

What I've Tried:

1. I've thought about creating the simulator with a high birth rate so that it creates several new truths at the first time step. Then I could lower the birth rate for the next time steps. But the number of targets that are made will still vary by the Poisson distribution. I want to dictate the exact number of targets that exist.

2. The MTT tutorial defines two truths which exist at the start and continue for the entire simulation. But then we have to manually iterate through all the time steps and fill the truth paths. I want to use the Simulator objects because I can pass them easily into detectors.

Any thoughts about how to do this? Thanks in advance!

[ekhunter123]

Update: I made a pull request to add some more parameters to the MultiTargetGroundTruthSimulator. It is now possible to pass in starting states for targets, and/or to tell the simulator how many targets you want to be randomly simulated from the start.