Using script operator to subtract 1 from custom float

[tyFlow]

It's not entirely clear to me what you're trying to do, but to decrement a value by 1 with a Script operator, you'd do something like this:

Code:

tf.SetCustomFloat(sInx, "hits", tf.GetCustomFloat(sInx, "hits") - 1);

That would go in the for-loop that iterates over all event particles and retrieves their simulation index (you can see this loop in the example script that is created when you create a new Script operator).