Introduction to Computational Modeling of Social Systems
Prof. Lars-Erik CedermanCenter for Comparative and International Studies (CIS)
Seilergraben 49, Room G.2, [email protected] Weidmann, CIS Room E.3 [email protected]
http://www.icr.ethz.ch/teaching/compmodels
Lecture, December 21, 2004
RePast Tutorial III
2
Today’s agenda
• GUI versus batch mode• How to create charts• GraphIPD• How to use spaces• How to create displays• GridIPD
3
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>
4
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)
