Brush Fire Covid Model
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WHAT IS IT?
Model showing another way besides an SIR model to model spread of an epidemic, using a brush fire as an example. This illustrates the complexity of possible outcomes that might match, say Covid-19 case rates show on the Johns Hopkins dashboard. https://coronavirus.jhu.edu/data/new-cases
HOW IT WORKS
Three parameters can be set with sliders -- 1) the percent of land ( green ) covered by dry brush ( brown), 2) the odds that a patch will catch fire if any adjacent patch is on fire. amd 3) The number of ticks that any patch "burns" before the fire on it goes out.
The random-seed used to generate the actual landscape and performance can be reused automatically or set to a given value, if desired, to replay a prior run.
HOW TO USE IT
Set the sliders to whatever you like. 51 and 51 and 3 are nice starting values. Set replay to ON
The random-seed used to generate the actual landscape can be reused by setting the switch, allowing the user to see the impact of the sliders versus random effectson the outcome ( the "epidemic curve" ).
The "speed" value can be left at 6 and just controls how fast the display runs if you don't use the slider at the very top.
Press Setup to restart with new values, press GO-ONCE to advance on tick, press GO to run continuously until the fire goes out, or press GO again to pause the run.
If you want and you are running locally versus on the web, press SNAPSHOT to save an image of your run with the parameters encoded in the name.
THINGS TO NOTICE
(suggested things for the user to notice while running the model)
THINGS TO TRY
values 33125-51-51-3 match the picture posted. values 2110948-51-51-3 are interesting.
to set a specific random seed:
- shut off replay
- turn on ask-for-seed
- click SETUP, it will ask for the seed, type it in
- turn off ask-for-seed
- turn on replay
- click GO
EXTENDING THE MODEL
NETLOGO FEATURES
RELATED MODELS
There are other covid and fire models in the commons.
CREDITS AND REFERENCES
Copyright (c) 2021 R. Wade Schuette
Comments and Questions
globals [ stopFlag maxTicks burnTime peakCaseCount newSeed couldGet didGet pctSusGot ] patches-own [ burnedTicks ] to setup ;; persist the last random seed across the clear-all command if newSeed = 0 [ set newSeed 33125 ] let saveseed newSeed clear-all set newSeed saveseed set stopFlag false set maxTicks 100 set burnTime burnTicks set peakCaseCount 0 ;; ============= allow replay of interesting saved prior cases ============= if ( replay = false ) [ ifelse askforseed? = true [ set newSeed read-from-string user-input "Enter a new random integer:" print ( word "User entered new random seed: " newSeed ) ] [ set newSeed random 12345678 print ( word "Computer picked a new random seed: " newSeed ) ] ] ;;========================================= random-seed newSeed print ( word "Using random seed: " newSeed ) ask patches [ ;; set pcolor brown ;; <<<<<<<<<<<<<< ;; becomes ifelse (random 101 < pctDryBrush ) [ set pcolor brown ] [ set pcolor green ] set burnedTicks 0 ] set couldGet count patches with [pcolor = brown ] print ( word couldGet " patches are brown ") ;;======================================== ask patch 0 0 [ set pcolor red ] reset-ticks end to go let nodisp "no-display" let disp "display" if (stopFlag = true) [ ;;set couldGet count patches with [pcolor = brown ] ;;done in setup above set didGet count patches with [pcolor = black ] set pctSusGot floor (100 * didGet / couldGet ) print (word "Of " couldGet " brown patches, " didGet " burned, or " pctSusGot " percent.") stop ] ;;========================================= every ( 1 / speed ) [ ;;======================================== if not netlogo-web? [ run nodisp ] ;;======================================== ask patches with [pcolor = brown] [ if any? neighbors with [ pcolor = red and burnedTicks > 0 ] [ ;; flip a coin if ( random 101 < oddsCatchIfExposed ) [ set pcolor red set burnedTicks 0 ] ] ] ;;========================================= ask patches with [pcolor = red ] [ set burnedTicks ( burnedTicks + 1 ) if ( burnedTicks > burnTime ) [ set pcolor black ] ] ;;========================================= if not netlogo-web? [ run disp ] let activeCaseCount count patches with [pcolor = red ] if (activeCaseCount > peakCaseCount ) [ set peakCaseCount activeCaseCount ] ;;========================================= tick if ( ticks >= maxTicks ) [ set stopFlag true print (word "Maximum time has run out at time " ticks) ] if (0 = count patches with [pcolor = red] ) [ print ( word "The fire burned out at time " ticks) set stopFlag true ] ] end to snapthat ifelse netlogo-web? [ print "snapshot only works if the model is downloaded" ] [ let fname (word "brush-" newSeed "-" oddsCatchIfExposed "-" pctDryBrush "-" burnTicks ".png" ) print (word "Saving file " fname ) let savecommand "export-interface fname" run savecommand ] end
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Attached files
File | Type | Description | Last updated | |
---|---|---|---|---|
Brush Fire Covid Model.png | preview | Preview for 'Brush Fire Covid Model' | almost 3 years ago, by R. Wade Schuette | Download |
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