Creating a population of agents
In AnyLogic you can create a number of agents of the same type simply by creating an agent population. You can build scalable systems by creating agent populations with the number of agents defined by a parameter of the model.
To create a population of agents
- Drag the
element from the
palette on the diagram of the agent type where you want to create the population of agents (usually -
dialog box will open.
Population of agents. The wizard will take you to the next step.
- If you already have some custom agent types in your model, you will be asked whether you want to create a new type of agent (I want to create a new agent type
option), or use the existing agent type (I want to use an existing agent type). Click
- Specify the
Agent type name
Person). You will see that the
Agent population name
- Choose whether you want to read agent attributes
or create a new agent type "from scratch".
- If you plan to use the agents of this type in the flowcharts (e.g. in the Process Modeling Library flowchart, or as a pedestrian in Pedestrian Library flowchart), select the checkbox
Agent will be used in flowcharts
and then choose the role for this agent from the drop-down list on the right. Depending on the chosen role, you will obtain access to role-specific API which extends beyond the API of a generic agent type. Click
- Specify the animation shape for the agents of this type. If you want the agents to be animated both in 2D and 3D, choose
and select the animation shape from the list below. If you need the shape that is shown in 2D only, choose
2D. Choose the shape from the list or, if no shapes satisfy your needs, choose
None. You can draw animation of the agent type on its graphical diagram later. When done, click
Specify the parameters for this agent type. Click
in the list on the left to create a new parameter. Having selected a parameter in this list, you can set its name, type, and initial value using the controls in the panel on the right. To remove the parameter, select it and click
button at the bottom of the list. Click
after you have finished defining the required parameters for this agent type.
- On the next page of the wizard you have to define the initial number of agents in the population. Choose whether you want to
Create population with
a specified number of agents, or you want to
Create initially empty population
and add agents later on dynamically (e.g. in the
Main). To proceed, click
- Next, you have to configure the environment where the agents of this population will live. Choose the type of the space (Continuous,
Discrete), and configure it using the controls below. Having chosen the continuous or discrete space type, define the space dimensions, width, and height, in the
fields (in the case of discrete space, you should also define the number of rows and columns that make up the space, in the
drop-down list allows you to choose how the network of agent contacts should be created. You can find more information on agent networks
- You can get AnyLogic to randomly locate agents of this population in the space. To do this, select the option
Apply random layout.
to end the process.
When finished, you will see the
element on the diagram - it is
agent population. The population contains the specified number of agents - instances of the
agent type. You can see the created agent type in the model tree (in the figure below it is
Open the diagram of this agent type by double-clicking it in the
view. You will see the animation and parameters you have chosen for this agent. You can add variables, parameters, statecharts, and any other elements defining the agent state and behavior.
You can specify any expression evaluating to
type as a number of agents living in the population. Thus, you can parameterize the number of agents. You may need this to facilitate modifying the number of agents of several populations.
If you use a parameter as a replication factor of an agent population, AnyLogic creates a number of agents equal to the initial value of the parameter. However, AnyLogic does not automatically adjust the number of agents in case you change the
parameter at runtime. If such behavior is needed, you should use the
parameter change handler
to take care of creation and destruction of agents.
Accessing individual agents living in a population
In order to access any individual agent from
population, you can use
function, which takes an
of the agent in the vector, from
people.size() – 1.