demo downhill-in-bounds
Model was written in NetLogo 5.0.4
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__includes [ "diffuse-in-bounds.nls" ; Same as diffuse but only for patches in bounds. "output-wrap.nls" ; Same as output-print but wraps printed output. "sigfigs.nls" ; Like precision but specifies number of significant figures. "random-walk.nls" ; Random walk. "updownhill-in-bounds.nls" ; Like uphill/downhill but only for patches in bounds. ] patches-own [ wall? source? sink? redness ] turtles-own [ age ] globals [ ; Variable 'dt' not needed here if using System Dynamics Modeler. dt ; Time step. Automatically set in 'go' by 'per-capita-tau-leap'. ] to startup setup ; Might as well setup when model loaded. end to setup clear-all reset-ticks output-wrap 27 ; Set output box to wrap at column 27. output-wrap ( word "Demonstrates hill climbing with bounds. Blue patches are walls that block " "movement. The red property diffuses within bounds and the turtles attempt to " "follow the gradient downhill (from white to black).\n\n" "Choose the wall-density and number of sources-and-sinks, then press 'setup'. " "Note that the edges also act as walls.\n" ) output-wrap ( word "Press 'go' to start diffusing and movement. The rate of diffusion is determined by " "the log-diffusion and err-tolerance sliders.\n" ) ask patches [ set source? false set sink? false set wall? random-float 1 < wall-density if-else wall? [ set pcolor blue ] [ set redness 5 ] ] ask n-of sources-and-sinks patches with [not wall?] [ set source? true set redness 10 ] ask n-of sources-and-sinks patches with [not wall? and not source?] [ set sink? true set redness 0 ] color-patches ask patches with [not wall? and not source? and not sink?] [ sprout 1 [ set size 1 set color green set age random world-width ] ] end to go if ticks = 0 [ output-wrap ( word "Green turtles move downhill (from white to black), avoiding blue walls " "until they get too old or reach a black sink. Then they respawn at a random " "new location and continue downhill. Some turtles get stuck trying to push " "through walls. Meanwhile, the red property diffuses from " "the white sources to the black sinks.\n" ) ] ; assume err = fraction = diffusion-const * dt set dt inaccuracy / diffusion-const ask patches with [source?] [ set redness 10 ] ask patches with [sink?] [ set redness 0 ] if-else (neighborhood = "4 neighbors") [ diffuse4-in-bounds "redness" inaccuracy task [not wall?] ] [ diffuse-in-bounds "redness" inaccuracy task [not wall?] ] color-patches ask turtles [ if-else (neighborhood = "4 neighbors") [ set heading towards-downhill4-in-bounds task [ redness ] task [ not wall?] ] [ set heading towards-downhill-in-bounds task [ redness ] task [ not wall?] ] set age age + dt if sink? or age > world-width ; don't let get older than it takes to cross fraction of world [ move-to one-of patches with [not wall?] set age 0 ] ] random-walk-in-cone-bounds turtles dt 180 * sqrt dt task [not wall?] tick-advance dt end to-report diffusion-const ; Used by 'go' in call to 'diffuse-individual'. report 10 ^ log-diffusion end to-report inaccuracy ; Complement of accuracy, depends on err-tolerance. ; Used by 'go' in call to 'per-capita-tau-leap'. report 10 ^ ( err-tolerance ) end to color-patches ask patches with [ wall? = false ] [ set pcolor scale-color red redness 0 10 ] end
There is only one version of this model, created over 11 years ago by Rik Blok.
Attached files
File | Type | Description | Last updated | |
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demo downhill-in-bounds.png | preview | Preview for 'demo downhill-in-bounds' | over 11 years ago, by Rik Blok | Download |
diffuse-in-bounds.nls | extension | Same as diffuse but only for patches in bounds. | over 11 years ago, by Rik Blok | Download |
output-wrap.nls | extension | Same as output-print but wraps printed output. | over 11 years ago, by Rik Blok | Download |
random-walk.nls | extension | Random walk. | over 11 years ago, by Rik Blok | Download |
sigfigs.nls | extension | Like precision but specifies number of significant figures. | over 11 years ago, by Rik Blok | Download |
updownhill-in-bounds.nls | extension | Like uphill/downhill but only for patches in bounds. | over 11 years ago, by Rik Blok | Download |
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