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My understanding is that attractors within nodes should have a capacity of 1, in the sense that in a 3D animation, there should only be one agent per attractor. When I run the model, I am seeing two agent shapes on the same attractor while other attractors are empty.

Is this normal behavior? Is there a way to prevent this from happening?

Note that this is not happening all the time, but as the model is running, sometimes agents go to empty attractors, while other times they go to one that already has an agent.

Jaco-Ben Vosloo
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Emile Zankoul
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2 Answers2

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One option is to create a collection, simple ArrayList will do, of all the attractors

enter image description here

Then in the Process Modelling Block (PML) where you setup the attractor you have a function that returns an Attractor. I supply the agent here so that we can keep track of what agent is sent to which attractor so that we can put the attractor back into the available pile once the agent leaves the attractor location.

enter image description here

Here is the getAttractor function

enter image description here

It gets a random available attractor and then also saves the agent that is taking it to a map

If you want to free the attractor you can simple call this at any point that the attractor is freed

attractorsAvailable.add(mapAgentPerAttractor.get(agent));
mapAgentPerAttractor.remove(agent);

Here is the final result as well as a comparison where we are replciating the problem you described

enter image description here

Jaco-Ben Vosloo
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this is totally possible... and how to avoid depends on your model in particular.

The attractors ONLY define where your agents are going to be inside a node, and there's no rule that states that you can't have many agents in the same attractor.

AnyLogic sends the agents to the attractors in the order in which they are created, and if you have 10 attractors and 10 agents initially went to the attractors if agent 3 leaves the attractor, the next agent will not go to attractor 3, instead it will go to attractor 1, then the next one will go to attractor 2, following the same order...

If you want to avoid it in general, you should specify explicitly to what attractor your agent should go.

What i do is i create a class and i associate it to that attractor and set up a variable that defines if the attractor is occupied or not...

Then you need to create additional logic to send the agents somewhere else if all the attractors are occupied

Felipe
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  • It's too bad, but at least glad to hear there isn't anything wrong with the model because of what I'm seeing. Thanks a lot for your answer! – Emile Zankoul Nov 23 '20 at 17:03