State

Every agent has a private state. Is the agent of height 1 or height 2? Is the agent's name "foo" or is its name = "bar"? These properties are expressed and saved on the agent's state.
Your agents can have any fields you want. Here's an agent that uses the Monte-Carlo method to approximate the value of pi via randomness:
// LeaderAgent
{
    agent_name: "leader",
    behaviors: ["spawn_samples.js", "estimate_pi.js"],
    spawned_datapoints: 0,
    neighbor_points: 0,
    pi_estimate: 0,
    position: [0, 0, 0],
    search_radius: 1,
}
Notice how we use multiple custom fields to store data in the agent.
Getting and Setting State
The state object has accessor methods for getting and setting state.
state.get(field_name) : returns the value of the field
state.set(field_name, value) : sets the field as the value
Example:
This behavior takes in the current state and context of the agent, adds 1 to the age property stored on the state, and then returns the state.
JavaScript
Python
JavaScript
const behavior = (state, context) => {
    let age = state.get("age");
    age += 1;
    state.set("age", age);
}
Python
def behavior(state, context):
    age = state.get("age")
    age += 1
    state.set("age", age)
Important: Only the agent can modify its own state. If an agent wants to prompt another agent to perform a state change, it can send a message to trigger an update.
Agents can read one another's state - for example if agent "foo" is a neighbor of agent "bar", agent "bar" can access the fields of agent "foo", it just can't make any changes to those fields. That's what makes the state private.
Modify
HASH also has a "modify" helper function which allows you to make certain state changes a one-liner:
state.modify(field_name, function) 
will allow you to pass a function that will be run on the given field in the agent's state. The above example can now be written like so:
Javascript
Python
Javascript
const behavior = (state, context) => {
    state.modify("age", age => age + 1)
}
Python
# We haven't yet enabled this helper function for Python
The state value will be set to the return value of the function. If you use a method that modifies a variable in place, likeArray.push(x)the return value is x and not the modified array.
Reserved Fields
While an agent can store arbitrary data in its own state, some state values have special meaning in HASH. The fields below are all reserved, in addition to fields tied to visualization which can be found here.
{ 
  agent_id: string // auto-created identifier. Agents receive messages to their ID.
  agent_name: string // optional identifier. Agent's receive messages to their name. 
  behaviors: [] // Filenames of the behaviors that the agent apply to advance their state every simulation step N to N+1. 
  messages: [] // Outbound messages from agent 
  position: [x, y, z] // displays agents in the viewer and used to calculate neighbors 
  search_radius: number // context.neighbors() will return a list of all the agents within the search radius
  direction: [x, y, z] // Will affect the visualization of the agent. Can be used for custom logic
  velocity: [x, y, z] // Will affect the visualization of the agent. Can be used for custom logic
  color: string // Color of the agent
  rgb: [r, g, b] // Color of the agent represented as an rgb array
  height: number // Height of the agent in the 3D Viewer
  scale: [x, y, z] // Agent model will be scaled along the corresponding axes
  shape: string // Determines the shape of the agent in the 3D Viewer
  hidden: boolean // Determines whether the agent is hidden in the 3D Viewer
  position_was_corrected: boolean // Used by the agent whenever agents reach topology bounds
}
Agents
Context
Last updated 1 week ago