On Oct 25, 2015, at 3:39 AM, Ernesto Carrella <[log in to unmask]> wrote: > It seems like using elements() to bag agents and then step them in a for loop is a recipe for artifacts: agents in the top left corner always act before agents in the bottom right. Bag vals = grid.elements(); vals.shuffle(state.random); And you're ready to go. > I usually do what Russell does, keeping a reference to agents in a separate collection and stepping that, but I prefer an ArrayList to aBag; partially because of generics but mostly because I can call Collections.shuffle(agentList,random) and randomize their order before stepping them. I would recommend strongly against using java.util.Random, and hence Collections.shuffle(...) > The only caveat is that MersenneTwisterFast is not a kosher Random object so you can’t pass it directly, but you can just pass a seed from the MASON randomizer to a standard Java one (or extend the MASON one so that it fulfills Randominterface). Again: it is unwise to use java.util.Random in a simulation. Sean