Programming for Social Scientists

Lecture 8UCLA Political Science 209-1: Programming for Social Scientists

Winter 1999

Lars-Erik Cederman & Benedikt Stefansson

Today’s topics

• More graphics

• Using probes– With GUI– To get and manipulate data

• Probes in action: The Script class

• Overriding methods

Changing the raster graphics

• Want to put a black border around each square on the lattice

• In order to do so must “paint” each tile independently

• Solution: A new message in ObserverSwarm

Raster fromGridIPD

New Raster

Changes in ObserverSwarm.m

• Need to catch the display message from each agent and implement new drawing method

In -buildObjects: worldDisplay = [ModObject2dDisplay createBegin: self]; [worldDisplay setDisplayWidget: (id <Raster>) self];

[worldDisplay setDiscrete2dToDisplay: [modelSwarm getWorld]];

[worldDisplay setObjectCollection: [modelSwarm getPlayers]];

[worldDisplay setDisplayMessage: M(drawSelfOn:)];

[worldDisplay setSizeFactor: sizeFactor];

worldDisplay = [worldDisplay createEnd];

Changes in ObserverSwarm.m (2)

• Agents call the “displayWidget” which is actually the ObserverSwarm and we process the information before calling the raster

-drawPointX: (int) posX Y: (int) posY Color: (int) type {

[worldRaster fillRectangleX0: sizeFactor*posX

Y0: sizeFactor*posY

X1: sizeFactor*(float)(posX+0.9)

Y1: sizeFactor*(float)(posY+0.9)

Color: type];

return self;

}

How it works

Raster

Object2dDisplay

ObserverSwarm

Agent

ObserverSwarm

-drawPointX:Y:Color:-drawPointX:Y:Color:

-fillRectangleX0:Y0:X1:Y1:-fillRectangleX0:Y0:X1:Y1:

-drawSelfOn:-drawSelfOn:

-makeProbeAtX:Y:-makeProbeAtX:Y:

Useful methods in Raster

- fillRectangleX0: (int)x0 Y0: (int)y0 X1: (int)x1 Y1: (int)y1 Color: (Color)color

Fill a rectangle of given geometry and color.

- ellipseX0: (int)x0 Y0: (int)y0 X1: (int)x1 Y1: (int)y1 Width: (unsigned)penWidth Color: (Color)c

Draw an ellipse of given geometry, pen width, and color.

- lineX0: (int)x0 Y0: (int)y0 X1: (int)x1 Y1: (int)y1 Width: (unsigned)penWidth Color: (Color)c

Draw a line of given geometry, pen width, and color.

- rectangleX0: (int)x0 Y0: (int)y0 X1: (int)x1 Y1: (int)y1 Width: (unsigned)penWidth Color: (Color)c

Draw a rectangle of given geometry, pen width, and color.

ModelSwarm

bugList

Graphical probes

ObserverSwarm

Probe Probe

main

ObserverSwarm

How the probes come in...

ModelSwarm

A custom ProbeMapwith 4 MessageProbes

A custom ProbeMapwith 1 MessageProbe

ControlPanel isprovided by kernel

Brief overview of probes

• Two major uses for probes– To interface with an object

– To create a GUI to an object

• Interface with an object of two types– VarProbe: Probes an instance variable

– MessageProbe: Probes a method

• GUI utilities:– ProbeMap: Collection of Var and MessageProbes

Major Probe classes

Probe ProbeMap

CompleteProbeMap

CompleteVarMap

CustomProbeMap

MessageProbe

VarProbe

ObjectBase

ProbeLibrary

Creating graphic probe to object

• Check out instance of EmtpyProbeMap

• Attach VarProbe or MessageProbe to each variable or message to appear on GUI

• Put each probe on ProbeMap

• Ask probeDisplayManager to create actual widget Object

VarProbes

MessageProbeA ProbeMap1

2

3

4

Code for previous exampleprobeMap=[EmptyProbeMap createBegin: aZone];[probeMap setProbedClass: [self class]];probeMap=[probeMap createEnd];[probeMap addProbe: [probeLibrary

getProbeForVariable: ”someVar" inClass: [agent class]]];

...[probeMap addProbe: [probeLibrary getProbeForMessage:

”someVar" inClass: [agent class]] setHideResult: 1]];

[probeLibrary setProbeMap: probeMap For: [self class]];

[probeDisplayManager createProbeDisplayFor: modelSwarm];

Model

Observer

probeMap = [EmptyProbeMap createBegin: self];

[probeMap setProbedClass: [self class]];

probeMap = [probeMap createEnd];

[probeMap addProbe: [probeLibrary

getProbeForVariable: "worldXSize”

inClass: [self class]]]; [probeLibrary setProbeMap: probeMap

For: [self class]];

(also must execute CREATE_PROBE_DISPLAY macro

in ObserverSwarm)

Example: A variable probe

1

2 3

4

probeMap = [EmptyProbeMap createBegin: self];

[probeMap setProbedClass: [self class]];

probeMap = [probeMap createEnd];

[probeMap addProbe: [[probeLibrary

getProbeForMessage: ”setWorldXSize:”

inClass: [self class]]

setHideResult: 1]]; [probeLibrary setProbeMap: probeMap For: [self class]];

(also must execute CREATE_PROBE_DISPLAY macro

in ObserverSwarm)

Example: A message probe

1

2 3

4

A probe for ModelSwarm in IPD+createBegin: (id) aZone {

...

probeMap = [EmptyProbeMap createBegin: aZone];

[probeMap setProbedClass: [self class]];

probeMap = [probeMap createEnd];

[probeMap addProbe: [probeLibrary getProbeForVariable: "randomSeed"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "worldSize"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pALLC"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pTFT"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pATFT"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pALLD"

inClass: [self class]]];

[probeLibrary setProbeMap: probeMap For: [self class]];

...

Code for the ModelSwarm probe

[probeMap addProbe: [probeLibrary getProbeForVariable: "randomSeed" inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "worldSize” inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pALLC" inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pTFT"

inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pATFT” inClass: [self class]]];

[probeMap addProbe: [probeLibrary getProbeForVariable: "pALLD" inClass: [self class]]];

Graphical and non-graphical probes

• ProbeMaps are collections of variable and message probes that can be displayed graphically

• Probes can also be used without the graphical component to construct method calls dynamically at runtime

Dynamic message calling

• Probe library allows you to construct method calls dynamically

• Here selector and target are data to be determined at runtime

theProbe=[MessageProbe createBegin: zone];

[theProbe setProbedSelector: theSelector];

theProbe=[theProbe createEnd];

anIndex=[aCollection begin: zone];

while((aMember=[anIndex next])) {

theData=[theProbe doubleDynamicCallOn:aMember]];

[self doSomething: theData];

}

Using probes to collect statistics

• Averager object can probe collection of objects and return average, total, min, max and count

• One use: Use data as argument to printf() statement to collect statistics

Averager

EZGraph

EZBin

Objectbase

Entropy

EZDistribution

Probe

Printing out data using Averager

• Creating:averager =[Averager createBegin: zone];

[averager setCollection: theCollection];

[averager setProbedSelector: theSelector];

averager=[anAverager createEnd];

• Using:[averager update];

printf(“%4.3f %4.3f %4.3f\n”,

[averager getMin],

[averager getAverage],

[averager getMax]);

Scripting with method probes

• Script class reads script file from disk and creates message probes

• Each line of script defines:

access t method arg1 … argN

• Where access is either – method name (get target obj)

– model (target is model)

• Creating a script:script=[Script create: self];

[script setFile: "scriptfile"];

[script logEvents: ”logfile"];

[script buildActions: self];

[script activateIn: self];

• Sample script:# A comment

@begin

model 2 printX:Y: 1 2

model 4 printX:Y: 2 4

# Another comment

model 8 shockMarketTo: -1

getMarket 20 setAlpha: 70

getMarket 30 setAlpha: 50

@end

Example: Scripting the IPD

In ModelSwarm.m:

-activateIn: (id) swarmContext {

[super activateIn: swarmContext];

script=[Script create: self];

[script setScriptFile: "script.txt"];

[script buildActions: self];

[script activateIn: self];

return self;

}

-invadeWithAllD: (int) n {

int i;

id agent,index;

if(n > [playerList getCount])

n=[playerList getCount]-1;

[self shuffle: playerList];

index=[playerList begin: self];

while(i<n && (agent=[index next])){

[agent setPlayerType: 3];

i++;

}

return self;

}

Example:Scripting the IPD (cont)

• Activate ModelSwarm in ObserverSwarm

• Example script triggers an invasion of ALL-D at time step 15 and 20

script.txt

# Comment

@begin

model 15 invadeWithAllD: 100

model 20 invadeWithAllD: 200

@end

The script searches in ModelSwarm for selector

Time step for action