Creating a population of
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
- Drag the Agent
element from the Agent
the diagram of the agent type where you want to create the
population of agents (usually - Main
type). The New agent
dialog box will open.
- Select 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 Next.
- Specify the Agent type name (e.g. Person). You will see that the Agent population name changes automatically.
- Choose whether you want to read agent
attributes from database 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.
- Specify the
animation shape for the agents of this type. If you want the agents to be animated both in 2D and 3D,
choose 3D 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 Next.
Specify the parameters for this agent type. Click <add new...>
in the list on the left to create a new parameter. Having selected a parameter in
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 Next 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 Startup code of Main). To proceed, click Next.
- Next, you have to configure the environment where the agents of this population will
live. Choose the type of the space (Continuous,
GIS, or 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 Size fields (in the case of discrete
space, you should also define the number of rows and columns that make up the
space, in the Cells fields).
- The Network
type drop-down list allows you to choose
how the network of agent contacts should be created. You can find more
information on agent networks here.
- You can get AnyLogic to randomly locate agents of this population in the space. To do this, select the option Apply random layout.
- Click Finish to end the
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 Person):
Open the diagram of this agent type by double-clicking it in the Projects
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 integer
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
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 people
population, you can use people(index)
function, which takes an index of the agent in the vector, from 0 to people.size() – 1.