Random Walker - Revision history

Fei at 17:41, 14 November 2006

2006-11-14T17:41:49Z

@@ Line 91: / Line 91: @@
     LastDirection = IF (Location EQ SOURCE Location) THEN LastDirection ELSE ROUND(DIRECTION(SOURCE Location, Location))
   ENDMP
 ==Suggested Experiments==
 To explore this cellular automata model further, try the following:

Fei: /* Model Code Exploration */

2006-11-14T17:39:53Z

Model Code Exploration

← Older revision		Revision as of 17:39, 14 November 2006
Line 14:		Line 14:
	In the following sections we will examine all of the model files for this model. Note that instead of downloading the zip file above, you could just copy the text in the boxes below into a text editor and save it with the appropriate name (Section title). Opening the resulting .scn file in the SELES simulator would run this model.		In the following sections we will examine all of the model files for this model. Note that instead of downloading the zip file above, you could just copy the text in the boxes below into a text editor and save it with the appropriate name (Section title). Opening the resulting .scn file in the SELES simulator would run this model.

	===~~Consume~~.scn===		===RandomWalker.scn===
	Seles Scenario		Seles Scenario
	~~Model~~.sel		RandomWalker.sel
	SimPriority Low Priority		SimPriority Low Priority

	===~~Model~~.sel===		===RandomWalker.sel===
	Seles Model		Seles Model
			Model Size: 200, 200
	Time Units: Step kiloStep 1000 1000		Time Units: Step kiloStep 1000 1000
	Landscape Events:		Landscape Events:
	~~Producer~~.lse DEBUG		RandomWalker.lse DEBUG
	~~Consumer.lse DEBUG~~		Global Constants:
	~~Update.lse DEBUG~~		MaxNumPresent = 100
	Spatial Variables:		Spatial Variables:
	~~LSState~~[3]		NumPresent[MaxNumPresent]
	~~PrevLSState[3]~~
	~~Legends:~~
	~~LSStateTypes = {0:Uncolonised, 1:Producer, 2:Consumer}~~
	Global Variables:		Global Variables:
	~~pInitialProducer~~ = ~~0.01~~		nInitial = MaxNumPresent
	~~pInitialConsumer = 0.01~~
	~~pSpreadProducer = 0.1~~
	~~pSpreadConsumer = 0.2~~
	~~pDeathProducer = 0.01~~
	~~pDeathConsumer = 0.05~~
	~~// SpreadRateProducer = 1~~
	~~// SpreadRateConsumer = 1~~
	Output Frequency: 1		Output Frequency: 1

	===~~consumer~~.lse===		===RandomWalker.lse===
	// ~~Process based~~ definition for ~~consumber behaviour in producer~~/~~consumer model~~		/* This file contains a landscape agent definition for a random walker */
	~~LSEVENT~~: ~~Consumder~~		LSAGENT: RandomWalker
	DEFINITIONS		DEFINITIONS
	LAYER: ~~LSState, PrevLSState~~		LAYER: NumPresent
	GLOBAL CONSTANT: ~~Uncolonised, Producer, Consumer~~		GLOBAL VARIABLE: nInitial
	~~GLOBAL~~ VARIABLE: ~~pInitialConsumer, pSpreadConsumer, pDeathConsumer //~~, ~~SpreadRateConsumer~~		GLOBAL CONSTANT: MaxNumPresent
			AGENT VARIABLE: LastDirection, StartLoc
	ENDDEF		ENDDEF
	// ~~Just start once~~		MOVELOCATION
	~~RETURNTIME =~~ 0		REGION CENTRED(0,1.5,WRAPPED)
	// ~~Initialize~~ in ~~an empty cell~~		ENDML
	~~PROBINIT~~ = ~~IF LSState EQ Uncolonised THEN~~ ~~pInitialConsumer ELSE 0~~		INITIALSTATE
			INITIALSTATE = 1
			// nInitial = CLAMP(nInitial, 1, MaxNumPresent)
			ENDIS
			/*
			AGENTLOCATION
			REGION RECT(0,0,0,0)
			ENDAL
			*/
			NUMAGENTS
			NUMAGENTS = nInitial
			NumPresent = MIN(NumPresent + 1, MaxNumPresent)
			// Pick a start direction in one of the cardinal directions
			LastDirection = 45 * FLOOR(UNIFORM(0,8))
			StartLoc = Location
			ENDNA
			POPULATIONTIME
			POPULATIONTIME = 1
			PAUSE(50)
			ENDPT
	TRANSITIONS		TRANSITIONS
	// ~~Decide if~~ this cell ~~survives~~		TRANSITIONS = TRUE
	~~Dies~~ = ~~UNIFORM~~(0,1) ~~< pDeathConsumer~~		ENDTR
	// If the ~~consumer is dying~~		MOVEPROB
	IF ~~Dies~~		// BEFORE MOVING: These expressions will be evaluated at
	~~LSState = Uncolonised~~		// all potential move locations
			// For a correlated random walk
			// For the current location, assume direction is the same
			IF (Location EQ SOURCE Location)
			dirDiff = 0
			// Otherwise, compute the angel between the current direction and direction to this cell
			ELSE
			dirDiff = LastDirection - ROUND(DIRECTION(SOURCE Location, Location))
			dirDiff = \|dirDiff\|
			// Ensure we consider smallest angle between the two directions
			dirDiff = IF dirDiff > 180 THEN 360 - dirDiff ELSE dirDiff
	ENDFN		ENDFN
	~~TRANSITIONS~~ = ~~!Dies~~		// MOVEPROB = IF dirDiff EQ 0 THEN 1 ELSE (1/dirDiff)^0.5
	~~LSState~~ = ~~Consumer~~		// MOVEPROB = 1/MAX(1,DISTANCE(Location, StartLoc))
	~~ENDTR~~		MOVEPROB = 1
	~~SPREADTIMESTEP~~ = 1 //~~SpreadRateConsumer~~		// AFTER MOVING: These expressions will be evaluated only
	~~SPREADLOCATION~~		// at the chosen move location
	~~REGION CENTRED~~(0,1~~, WRAPPED~~)		SOURCE NumPresent = MAX(0,SOURCE NumPresent - 1)
	~~ENDSL~~		NumPresent = MIN(NumPresent + 1, MaxNumPresent)
	~~SPREADPROB~~		LastDirection = IF (Location EQ SOURCE Location) THEN LastDirection ELSE ROUND(DIRECTION(SOURCE Location, Location))
	~~// Always spread to the same cell~~ (~~self~~)~~, and spread probabilistical to neighbouring producer cells~~		ENDMP
	~~SPREADPROB~~ = IF Location EQ (SOURCE Location) ~~THEN 1~~
	~~ELSE IF PrevLSState EQ Producer~~ ~~THEN pSpreadConsumer~~
	~~ELSE 0~~
	~~ENDSP~~

	===producer.lse===		===producer.lse===

Fei at 17:34, 14 November 2006

2006-11-14T17:34:48Z

← Older revision		Revision as of 17:34, 14 November 2006
Line 4:		Line 4:
	==Screenshot==		==Screenshot==

	[[Image:~~Consumer~~.gif]]		[[Image:NumPresent.gif]]

	==Download Model==		==Download Model==

	Download the .scn, .sel and .lse files by clicking on the following link: [[Image:~~ProducerConsumer~~.zip]]		Download the .scn, .sel and .lse files by clicking on the following link: [[Image:RandomWalker.zip]]

	==Model Code Exploration==		==Model Code Exploration==

Fei at 17:30, 14 November 2006

2006-11-14T17:30:24Z

New page

==Summary==

==Screenshot==

[[Image:Consumer.gif]]

==Download Model==

Download the .scn, .sel and .lse files by clicking on the following link: [[Image:ProducerConsumer.zip]]

==Model Code Exploration==

In the following sections we will examine all of the model files for this model. Note that instead of downloading the zip file above, you could just copy the text in the boxes below into a text editor and save it with the appropriate name (Section title). Opening the resulting .scn file in the SELES simulator would run this model.

===Consume.scn===
Seles Scenario
Model.sel
SimPriority Low Priority

===Model.sel===
Seles Model
Time Units: Step kiloStep 1000 1000
Landscape Events:
Producer.lse DEBUG
Consumer.lse DEBUG
Update.lse DEBUG
Spatial Variables:
LSState[3]
PrevLSState[3]
Legends:
LSStateTypes = {0:Uncolonised, 1:Producer, 2:Consumer}
Global Variables:
pInitialProducer = 0.01
pInitialConsumer = 0.01
pSpreadProducer = 0.1
pSpreadConsumer = 0.2
pDeathProducer = 0.01
pDeathConsumer = 0.05
// SpreadRateProducer = 1
// SpreadRateConsumer = 1
Output Frequency: 1

===consumer.lse===
// Process based definition for consumber behaviour in producer/consumer model
LSEVENT: Consumder
DEFINITIONS
LAYER: LSState, PrevLSState
GLOBAL CONSTANT: Uncolonised, Producer, Consumer
GLOBAL VARIABLE: pInitialConsumer, pSpreadConsumer, pDeathConsumer //, SpreadRateConsumer
ENDDEF
// Just start once
RETURNTIME = 0
// Initialize in an empty cell
PROBINIT = IF LSState EQ Uncolonised THEN pInitialConsumer ELSE 0
TRANSITIONS
// Decide if this cell survives
Dies = UNIFORM(0,1) < pDeathConsumer
// If the consumer is dying
IF Dies
LSState = Uncolonised
ENDFN
TRANSITIONS = !Dies
LSState = Consumer
ENDTR
SPREADTIMESTEP = 1 //SpreadRateConsumer
SPREADLOCATION
REGION CENTRED(0,1, WRAPPED)
ENDSL
SPREADPROB
// Always spread to the same cell (self), and spread probabilistical to neighbouring producer cells
SPREADPROB = IF Location EQ (SOURCE Location) THEN 1
ELSE IF PrevLSState EQ Producer THEN pSpreadConsumer
ELSE 0
ENDSP

===producer.lse===
// Process based definiton of producer behaviour in producer/consumer model
LSEVENT: Producer
DEFINITIONS
LAYER: LSState, PrevLSState
GLOBAL CONSTANT: Uncolonised, Producer, Consumer
GLOBAL VARIABLE: pInitialProducer, pSpreadProducer, pDeathProducer //, SpreadRateProducer
ENDDEF
// Just start once
RETURNTIME = 0
// Initialize in an empty cell
PROBINIT = IF LSState EQ Uncolonised THEN pInitialProducer ELSE 0
TRANSITIONS
// Decide if this cell survives
Dies = UNIFORM(0,1) < pDeathProducer
// If the producer is dying
IF Dies
LSState = Uncolonised
ENDFN
TRANSITIONS = (!Dies)
LSState = Producer
ENDTR
SPREADTIMESTEP = 1 //SpreadRateProducer
SPREADLOCATION
notEaten = PrevLSState EQ Producer // check that the producer wasn't eaten during the last step
REGION CENTRED(0, 1, WRAPPED)
DECISION notEaten // don't spread if eaten (i.e. stop process)
ENDSL
SPREADPROB
// Always spread to the same cell (self), and spread probabilistically to empty neighbouring cells
SPREADPROB = IF Location EQ (SOURCE Location) THEN 1 // spread to same cell
ELSE IF PrevLSState EQ Uncolonised THEN pSpreadProducer
ELSE 0
ENDSP

===update.lse===
// Event to update time step
LSEVENT: Update
DEFINITIONS
LAYER: LSState, PrevLSState
ENDDEF
RETURNTIME
RETURNTIME = 1
PrevLSState = LSState
ENDRT
NUMCLUSTERS = 0

==Suggested Experiments==

To explore this cellular automata model further, try the following: