Computational Models of Social Systems

Prof. Lars-Erik CedermanCenter for Comparative and International Studies (CIS)

Seilergraben 49, Room G.2, lcederman@ethz.chLuc Girardin, CIS Room G.1 girardin@icr.gess.ethz.ch

http://www.icr.ethz.ch/teaching/compmodels

Lecture, June 1, 2004

RePast Tutorial V

2

Invitation

Einführungsvorlesung:Agent-Based Models of Geopolitical Processes

Thursday, June 10, 2004, 17:15ETH Zentrum, HG, Auditorium

maximumApéro follows

3

Today’s agenda

• More on the GUI mode…– Probes– How to create property descriptors– How to create custom actions

• Introducing the batch mode– How to use parameters and parameter

files– How to collect data

• ExperIPD

4

Probes

• Probes allow the user to view and manipulate single agents

• Require the display surface to be “probeable”

• Variables become available through introspection using the get-set-methods (with set-methods necessary for changes)

5

How to create property descriptors

• To adjust parameters at startup or when the simulation is paused

• Can be applied to both models and agents

• Setup through the pre-defined descriptors variable of SimpleModel

6

How to create property descriptors (cont.)

• Drop-down list:public void setup() { super.setup();

Hashtable h1 = new Hashtable(); h1.put(new Integer(0), "Von Neumann"); h1.put(new Integer(1), "Moore"); ListPropertyDescriptor pd = new ListPropertyDescriptor("Type", h1); descriptors.put("Type", pd);}

public void setType(int type) { this.type = type;}

7

How to create property descriptors (cont.)

• Numerical slider:

public void setup() { super.setup();

RangePropertyDescriptor d = new RangePropertyDescriptor("NumAgents", 10, 100, 20); descriptors.put("NumAgents", d);}

public void setNumAgents(int numAgents) { this.numAgents = numAgents;}

8

How to create custom actions

• Modify the simulation while it is running

• Setup through modelManipulator variable of SimpleModel

• Works for buttons, check boxes, sliders, and arbitrary Java components

9

How to create custom actions (cont.)

• modelManipulator.addButton("Clear Space", new ActionListener() { public void actionPerformed(ActionEvent e){ space.clear(); }});

• modelManipulator.addSlider("Slider", 0, 100, 10, new SliderListener());

• modelManipulator.addCheckBox("Show/Hide", new CheckBoxListener(), false);

• modelManipulator.addComponent(Component c);

10

Failed invasion of TFT in ALLD-World

ALLD

ALLD ALLD ALLD

ALLD

TFT

ALLD ALLD

ALLD3

3

3

3 84

4

4

4+4+4+8 4

= 5.0

3+3+3+3 4

= 3.0

ALLD:

TFT:

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Successful invasion of two TFT players in ALLD-World

ALLD

ALLD ALLD ALLD

ALLD

TFT

ALLD ALLD

TFT

4+4+4+8 4

= 5.0

3+3+3+12 4

= 5.25

ALLD:

TFT:

ALLD

ALLD

ALLD3

3

3

12 123

3

3 84

4

4

12

Further spread of TFT players in ALLD-World

TFT

ALLD TFT TFT

ALLD

TFT

TFT TFT

TFT

ALLD

ALLD

TFT

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Separating GUI and batch modes

Modelextends

SimpleModel

ModelGUIextendsModel

ModelBatchextendsModel

ExperIPDGraphIPD,GridIPD

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Working in batch mode

ParameterFile

ReplicationRuns

DataFile

StatisticsPackage

Batch Model

• Batch mode allows the user to rerun the model without using the GUI

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Subclassing a batch model

class Model extends SimpleModel { model variables

setup()

buildModel()

step()

main()}

class ModelBatch extends Model{ Batch variables (data recorder)

setup() { super.setup(); params = ... }

buildModel() { super.buildModel(); create data recorder }

step() { super.step(); record data }

main() { init.loadModel(m, "params.txt", true); }}

Parameter file

Batch mode

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How to use parameters

• Different purpose depending on context:– Batch mode: allow variables to be

changed through parameter files– GUI mode: show the variables in the

control panelpublic void setup() { super.setup(); params = {"NumPlayers", "PALLC", "PTFT", "PATFT", "PALLD", "PAdapt"};}

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How to use parameters (cont.)

• Requires accessor methods:

public void setup() { super.setup(); params = {"Variable", ...}}

public double getVariable() { return value;}

public void setVariable(double value) { this.value = value;}

Setters only required to

allow modification

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How to use parameter files

• Different effects depending on context:– GUI mode: set initial values– Batch mode: allow to run sweeps

• Usually defined in a file named params.txt

• Runs the simulation with values of 10, 20, and 30:

runs: 1Variable { start: 10 end: 30 incr: 10}

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How to use parameter files (cont.)

• Multiple parameters:

• Nestingruns: 10Food { start: 10 end: 30 incr: 10}

MaxAge { start: 10 end: 30 incr: 10}

runs: 1Food { start: 10 end: 30 incr: 10 { runs: 10 MaxAge { start: 0 end: 40 incr: 1 } }}

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How to use parameter files (cont.)

• Additional keywords:– set

defines a single numerical value as a constant for the entire collection of batch runs.

– set_booleandefines a boolean value (true / false).

– set_stringdefines a string value (without any white space).

– set_list,set_boolean_list, set_string_list define a space-separated list of values. A batch simulation will iterate through the list.

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How to collect data

• Recording of simulation states to:– archive simulation runs– further process the data into third-party

packages (e.g. Excel, Stata, SPSS, SAS, ...)

• Output format: Text files (comma, space or tab delimited)

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How to collect data (cont’d)

• Prepare for the measurements in buildModel()• Determine the duration of the simulations:

setStoppingTime(n);

• Create the data recorder with output to file data.txt:recorder = new DataRecorder(“./data.txt”,this);

• Add numeric streams using introspection:recorder.createNumericaDataSource(“X”,this,”computeX”);

• The output can be formatted with x number of digits before the decimal point, and y after…createNumericaDataSource(“X”,this,”computeX”,x,y);

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How to collect data (cont’d)

• Using introspection requires a method delivering the values

• It is also possible to use inner classes (see the Repast How-To Documentation)

• The data recorder has to be told to record and to write the data to file:recorder.record();

recorder.writeToFile();

• The user can change the data delimiter:recorder.setDelimiter(“ “);

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Typical output fileTimestamp: May 31, 2004 6:09:01 PM

Neighborhood: 0

NumOfTimeSteps: 200

PALLC: 0.25

PALLD: 0.25

PATFT: 0.25

PAdapt: 0.2

PTFT: 0.25

WorldSize: 16

"run" "tick" "Topology" "RngSeed" "ALLC" "TFT" "ATFT" "ALLD" "Payoff"

1 200.0 0 1 0.0 256.0 0.0 0.0 3.0000

2 200.0 0 2 0.0 256.0 0.0 0.0 3.0000

3 200.0 0 3 0.0 256.0 0.0 0.0 3.0000

4 200.0 0 4 0.0 256.0 0.0 0.0 3.0000

…

59 200.0 2 19 0.0 0.0 0.0 256.0 1.0000

60 200.0 2 20 0.0 0.0 0.0 256.0 1.0000

End Time: May 31, 2004 6:09:16 PM

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Replication results (N = 200)

0 6020 40

Number ofTFT-dominatedruns

Initial numberof TFT players