RePast Tutorial III

Introduction to Computational Modeling of Social Systems

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

Seilergraben 49, Room G.2, lcederman@ethz.chNils Weidmann, CIS Room E.3 weidmann@icr.gess.ethz.ch

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

Lecture, December 21, 2004

RePast Tutorial III

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Today’s agenda

• GUI versus batch mode• How to create charts• GraphIPD• How to use spaces• How to create displays• GridIPD

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Two modes of modeling

Organizations of agents

Animate agents

Data

Artificial world

Observer

Inanimate agents

If <cond>

then <action1>

else <action2>

If <cond>

then <action1>

else <action2>

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GUI features

Graphical user interfaces offer:• Customized parameter panel• Dynamic graphs• Graphical displays• Probes

GraphIPD

GridIPD

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Separating GUI and batch modes

Modelextends

SimpleModel

ModelGUIextendsModel

ModelBatchextendsModel

ExperIPDGraphIPD,GridIPD

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Subclassing a GUI model

class Model extends SimpleModel { model variables

setup()

buildModel()

step()

main()}

class ModelGUI extends Model{ GUI variables (graph)

setup() { super.setup(); params = ... delete old graphs }

buildModel() { super.buildModel(); create graph }

step() { super.step(); update graph }

...

main()}

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Types of plots and charts

• Time seriesuser defined variable(s) over time

• Histogrambar chart showing a variable’s distribution

• Scatter plotsnapshot of two variables

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Showing time series

• Main class: OpenSequenceGraphuchicago.src.sim.analysis.OpenSequenceGraph

• Extension: NetSequenceGraphSpecialized for network statistics (path length, cluster coefficient, density, ...). Note: agentList should implement the Node interface!

• Declaration:

public class ModelGUI extends Model {

private OpenSequenceGraph graph;

...

}

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Showing time series (cont.)

• Initialization: public void setup() { super.setup(); if (graph != null) graph.dispose(); }

• Instantiation: public void buildModel() { super.buildModel();

graph = new OpenSequenceGraph(“Graph", this); graph.setXRange(...); graph.addAxisTitles(...); graph.display(); }

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Showing time series (cont.)

•Updating: public void step() { super.step();

graph.step(); }

•Adding variables: graph.createSequence(“X", this,“getXValue");

Name of the method

returning the value to be displayed

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OpenSequenceGraph API

• addSequence(String name, Sequence seq, Color color, int markStyle)Adds a sequence with a specific name to be drawn in a user-defined color and points in a pre-defined style

• record() Records the data for this graph without updating the display

• setYAutoExpand(boolean autoExpand) Sets whether the y-axis scale will expand to include new points or not

• setYRange(double min, double max) Sets the initial range of the y-axis.

• writeToFile() Writes this graph to a file.

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Example: Scatter plot

Plot aPlot = new Plot("Test Plot");aPlot.addLegend(0, "Sin", Color.blue, Plot.FILLED_DIAMOND);

aPlot.addLegend(1, "Manual", Color.red); aPlot.setConnected(true); aPlot.display();

for (double i = 0; i < 100; i++) { aPlot.plotPoint(i, Math.sin(i), 0); } aPlot.plotPoint(3.0, 4.0, 1); aPlot.plotPoint(5.0, 1.4, 1); aPlot.updateGraph(); aPlot.fillPlot();

uchicago.src.sim.analysis.Plot

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Beyond RePast charts

• For tailor-made graphics,bypass RePast and developyour own custom classes

• Example can be found aspart of the GraphIPD model(CustomModelGUI).

• It is also possible to integrate third-party libraries:– Java3D: http://java.sun.com/products/java-media/3D/

– JFreeChart: http://www.jfree.org/jfreechart/– JMSL: http://www.vni.com/products/imsl/jmsl.html

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GridIPD: How to use spaces

• Two purposes:– Collection of agents– Spatial relationship of agents

• Discrete• Package: uchicago.src.sim.space• Declaration:

public class Model extends SimpleModel { protected Object2DGrid world; private int worldSize;

... }

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How to use spaces (cont.)

• Initialization: public void setup() { super.setup(); worldSize = 16; }

• Instantiation: public void buildModel() {

super.buildModel(); world = new Object2DGrid(worldSize, worldSize); for (int x = 0; x < worldSize; x++) for (int y = 0; y < worldSize; y++) { Player aPlayer = new Player(x,y,...); world.putObjectAt(x, y, aPlayer); agentList.add(aPlayer); } }}

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Types of spaces

• Boundaries– Grid– Torus

• Cell’s shape– Rectangular– Hexagonal

• Cell’s content– One object– Collection of agents

V1

0,0

0,1

0,20,3

0,4

1,0

1,1 1,3

1,41,2

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Classes

• Object2DGridA discrete two-dimensional grid whose cells may contain an object.

• Object2DTorus A discrete two-dimensional torus whose cells may contain an object.

• Multi2DGrid A two-dimensional grid whose cells can contain more than one Object. The order of the Objects in each cell is undefined.

• OrderedMulti2DGridA two-dimensional grid whose cell can contain more than one Object. The order of the Objects in each cell is first in, first out.

• Diffuse2DGridA discrete approximation of two-dimensional diffusion. The space itself is a toroidal (donut-shaped) grid whose cells contain doubles.

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Usage

• Random arrangement:Object2DGrid space = new Object2DGrid(spaceWidth, spaceHeight);for (int i = 0; i < numAgents; i++) { int x, y; do { x = Random.uniform.nextIntFromTo(0, space.getSizeX() - 1); y = Random.uniform.nextIntFromTo(0, space.getSizeY() - 1); } while (space.getObjectAt(x, y) != null);

MyAgent agent = new MyAgent(x, y, space); space.putObjectAt(x, y, agent); agentList.add(agent);}

• Moving agentspace.putObjectAt(x, y, null);space.putObjectAt(newX, newY, agent);

Random arrangeme

nt

One occupant per

cell

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Neighborhood

• Moore

getMooreNeighbors(int x, int y, int xExtent, int yExtent, boolean nulls)

• Von Neumann

getVonNeumannNeighbors(int x, int y, int xExtent, int yExtent, boolean nulls)

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How to create displays

• Displays: graphical presentations of agents and their environments

• Package: uchicago.src.sim.gui• Declaration:

public class ModelGUI extends Model { private DisplaySurface dsurf;

...

}Extends

JComponent

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How to create displays (cont.)

• Initialization: public void setup() { super.setup(); if (dsurf != null) dsurf.dispose();

DisplayConstants.CELL_WIDTH = 30; DisplayConstants.CELL_HEIGHT = 30; dsurf = new DisplaySurface(this, “2D Display"); registerDisplaySurface("Main", dsurf);

}

• Delegation to buildDisplay method: public void buildModel() { super.buildModel();

buildDisplay(); }

Size of a cell in pixels

Good practice!

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How to create displays (cont.)

• Instantiation: public void buildDisplay() {

Object2DDisplay display = new Object2DDisplay(world); display.setObjectList(agentList); dsurf.addDisplayable(display, "Display"); addSimEventListener(dsurf); dsurf.display();

}

• Updating: public void step() { super.step();

dsurf.display(); }

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How to create displays (cont.)

• Cell drawing: public class Player implements Drawable {

int x, y; public Player(int x, int y) { this.x = x; this.y = y; } public void draw(SimGraphics g) { g.setDrawingParameters(DisplayConstants.CELL_WIDTH * 2/3,

DisplayConstants.CELL_HEIGHT * 2/3, DisplayConstants.CELL_DEPTH * 2/3);

g.drawFastRoundRect(COLOR[type]); } public int getX() { return x; } public int getY() { return y; }

}

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SimGraphics API

• drawCircle(Color c)Draws a true circle with the specified color.

• drawFastRoundRect(Color c)Draws a rounded rectangle of the specified color.

• drawHollowOval(Color c)Draws a hollow oval in the specified color.

• drawStringInRoundRect(Color rectColor, Color stringColor, String text)Draws the specified string inside a rounded rectangle.

• ...• setDrawingParameters(int width, int height, int depth)Sets the parameters for the next drawing operation.

Usually faster than

drawRoundRect

No fill

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Drawable, space and display

Space Display Interface Object2DGrid Object2DDisplay Drawable

Object2DTorus Object2DDisplay Drawable

Diffuse2D Value2DDisplay N/A. Map to values to a ColorMap instead.

Multi2DGrid MultiObject2DDisplay Drawable

Multi2DTorus MultiObject2DDisplay Drawable

OrderedMulti2DGrid MultiObject2DDisplay Drawable

OrderedMulti2DTorus MultiObject2DDisplay Drawable

Object2DHexagonalGrid Object2DHexaDisplay Drawable

Object2DHexagonalTorus Object2DHexaDisplay Drawable

DiffuseHexagonal2D Value2DHexaDisplay N/A. Map to values to a ColorMap instead.

RasterSpace Object2DDisplay Drawable

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Snapshots and movies

• Snapshots:dsurf.setSnapshotFileName("snapshot");schedule.scheduleActionAtInterval(100, dsurf, "takeSnapshot");

• Moviesdsurf.setMovieName("movie.mov", DisplaySurface.QUICK_TIME);schedule.scheduleActionAtInterval(10, dsurf, "addMovieFrame");schedule.scheduleActionAtEnd(dsurf, "closeMovie");

snapshot-100.gif

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Advanced graphics

• Use network displays (see RePast How To document)

• Use custom Java drawing (see CustomGraphGUI of GraphIPD for an example)