breed [ limpets limpet ] globals [ ; Global variables time ; Time at the beginning of the time step, in hours favorable? ; TRUE during favorable hours of day ; Limpet parameters cost-feeding ; energy cost (J per half-hour) when feeding cost-resting ; energy cost (J per half-hour) when resting cost-start-resting ; energy cost (J per half-hour) for first time step of resting cost-stasis ; energy cost (J per half-hour) when using stasis ingestion ; food intake when feeding (mm3 per half-hour) max-gut-content ; maximum volume of food in gut (mm3) food-energy ; energy content of food (J/mm3) gut-process-rate ; max gut processing rate (mm3 per half-hour) max-energy-reserve ; maximum energy reserve (J) survival-if-rest ; Probability of surviving one time step when resting survival-if-active ; Probability of surviving one time step when feeding or in stasis in favorable period survival-if-active-unfavorable ; Probability of surviving when feeding or in stasis in unfavorable period ; Display variables feed-patches ; Agentsets of the patches used for feeding and resting rest-patches ; for display only the-dial ; A turtle that indicates time ; Flag variables first-pred-energy-output? ; used in test output for predicted daily energy ] limpets-own [ energy-reserves ; energy reserve (w) gut-content ; (g), mm3 activity ; "feeding", "resting", or "stasis" prev-activity ; activity in previous time step active-hours ; number of hours feeding or in stasis, over entire simulation daily-survival ; probability of surviving remainder of current day ] to setup ca reset-ticks ; Create and color the feeding and resting patches set feed-patches patches with [pycor >= 0] set rest-patches patches with [pycor < 0] ask feed-patches [ set pcolor grey ] ask rest-patches [ set pcolor blue ] ; set global and parameter values set time -0.5 ; Time at the end of the time step, in hours; initialize to -1 time step set favorable? true set cost-feeding 49.4 ; energy cost (J per half-hour) when feeding set cost-resting 6.23 ; energy cost (J per half-hour) when resting set cost-start-resting 135.7 ; energy cost (J per half-hour) for first time step of resting set cost-stasis 6.23 ; energy cost (J per half-hour) when using stasis set ingestion 70.7 ; food intake when feeding (mm3 per half-hour) set max-gut-content 207 ; maximum volume of food in gut (mm3) set food-energy 1.66 ; energy content of food (J/mm3) set gut-process-rate 23.6 ; max gut processing rate (mm3 per half-hour) set max-energy-reserve 231 ; maximum energy reserve (J) set survival-if-rest 1.0 ; Probability of surviving one time step when resting set survival-if-active 1.0 ; Probability of surviving one time step when feeding or in stasis set survival-if-active-unfavorable 0.0 ; Probability of surviving when feeding or in stasis in unfavorable period ; Flag variables set first-pred-energy-output? true ; create limpets create-limpets 1 [ set energy-reserves max-energy-reserve ; energy reserve (w) set gut-content 0 set active-hours 0 ; number of hours feeding or in stasis set daily-survival 1.0 ; Start in a resting patch set activity "resting" set shape "circle" set color red move-to one-of rest-patches ] crt 1 [ move-to patch (max-pxcor - 1) (max-pycor - 1) set shape "arrow" set heading 0 set color yellow set the-dial self ] end to go tick if ticks > 384 [ stop ] update-time ask limpets [ select-activity-3 set energy-reserves new-energy-with prev-activity activity energy-reserves gut-content set gut-content gut-content-with activity gut-content ] ask limpets [ survive ] if not any? limpets [ show (word "All limpets have died at tick: " ticks) stop ] update-output end to update-time ; A global procedure ; Each tick is 1/2 hour; time is in hours, and "time" is the time ; at the start of the time step set time time + 0.5 if time >= 24 [ set time 0.0 set favorable? true ask limpets [ set daily-survival 1.0 ] ] ; show time ask the-dial [ ifelse time < 12 [ set heading 360 * time / 12 set color yellow ] [ set heading 360 * (time - 12) / 12 set color black ] ] if time >= favorable-phase-length [ set favorable? false ] end to survive ; Survival includes two mortality sources ; First, starvation if energy-reserves <= 0.0 [ die ] ; Second, predation and desiccation let survival-of-time-step survival-with activity favorable? if random-float 1.0 > survival-of-time-step [ die ] set daily-survival daily-survival * survival-of-time-step end to-report energy-from-gut [ some-gut-contents ] ; Limpet (or Observer) reporter to calculate energy value of gut contents let energy-in-gut some-gut-contents * food-energy ; Energy (J) in gut contents let time-to-process some-gut-contents / gut-process-rate ; time (s) to process gut contents let respiration-to-process cost-resting * time-to-process ; Respiration (J) to process report energy-in-gut - respiration-to-process end to select-activity-3 ; A limpet procedure to select best activity ; Here, "activity" is activity used last time step ; In this version, maximize expected mean energy reserve until end of the current day ; Test output file. ; if ticks = 1 ; [ ; if file-exists? "select-activity-test-V3.csv" [ file-delete "select-activity-test-V3.csv" ] ; file-open "select-activity-test-V3.csv" ; file-type "tick,favorable?,gut-content,energy-reserve,prev-activity," ; file-type "daily-energy-if-feed,daily-survival-if-feed,fitness-feed," ; file-type "daily-energy-if-rest,daily-survival-if-rest,fitness-rest," ; file-print "daily-energy-if-stasis,survival-if-stasis,fitness-stasis,activity" ; file-close ; ] ; file-open "select-activity-test-V3.csv" ; file-type (word ticks "," favorable? "," gut-content "," energy-reserves "," activity ",") set prev-activity activity set daily-survival (survival-with "feeding" favorable?) ; this is updated in predicted-daily-energy let energy-if-feed new-energy-with activity "feeding" energy-reserves gut-content let gut-content-if-feed (gut-content-with "feeding" gut-content) let daily-energy-if-feed predicted-daily-energy-reserve-with energy-if-feed gut-content-if-feed "feeding" if (daily-energy-if-feed < 0.0) [ set daily-energy-if-feed 0.0 ] let fitness-if-feed daily-energy-if-feed * daily-survival ; file-type (word daily-energy-if-feed "," daily-survival "," fitness-if-feed ",") set daily-survival (survival-with "resting" favorable?) ; this is updated in predicted-daily-energy let energy-if-rest new-energy-with activity "resting" energy-reserves gut-content let gut-content-if-rest (gut-content-with "resting" gut-content) let daily-energy-if-rest predicted-daily-energy-reserve-with energy-if-rest gut-content-if-rest "resting" if (daily-energy-if-rest < 0.0) [ set daily-energy-if-rest 0.0 ] let fitness-if-rest daily-energy-if-rest * daily-survival ; file-type (word daily-energy-if-rest "," survival-if-rest "," fitness-if-rest ",") let fitness-if-stasis -999 ; Stasis is not possible if currently resting let gut-content-if-stasis 0 ; Variable created here to facilitate test output let daily-energy-if-stasis 0 ; Variable created here to facilitate test output let energy-if-stasis 0 ; Variable created here to facilitate test output if activity != "resting" [ set daily-survival (survival-with "stasis" favorable?) ; updated in predicted-daily-energy-reserve set gut-content-if-stasis (gut-content-with "stasis" gut-content) set energy-if-stasis new-energy-with activity "stasis" energy-reserves gut-content set daily-energy-if-stasis predicted-daily-energy-reserve-with energy-if-stasis gut-content-if-stasis "stasis" if (daily-energy-if-stasis < 0.0) [ set daily-energy-if-stasis 0.0 ] set fitness-if-stasis daily-energy-if-stasis * daily-survival ] ; file-type (word daily-energy-if-stasis "," daily-survival "," fitness-if-stasis ",") if prev-activity = "resting" [ if (fitness-if-feed > fitness-if-rest) [ ; switch from resting to feeding, otherwise do nothing and continue resting set activity "feeding" move-to one-of feed-patches set active-hours active-hours + 0.5 set color green ] ] if prev-activity = "feeding" [ ifelse (fitness-if-rest >= fitness-if-feed) and (fitness-if-rest >= fitness-if-stasis) [ ; switch to resting set activity "resting" move-to one-of rest-patches set color red ] [ ; decide whether to feed or use stasis ; Stasis is chosen if tied with feeding and gut is full ifelse (fitness-if-stasis > fitness-if-feed) or (fitness-if-stasis = fitness-if-feed and gut-content-if-feed = max-gut-content) [ ; switch from feeding to stasis set activity "stasis" move-to one-of feed-patches set active-hours active-hours + 0.5 set color yellow ] [ ; continue feeding set activity "feeding" move-to one-of feed-patches set active-hours active-hours + 0.5 set color green ] ] ] if prev-activity = "stasis" [ ifelse (fitness-if-stasis >= fitness-if-rest) and (fitness-if-stasis >= fitness-if-feed) [ ; continue using stasis; do not move set activity "stasis" set active-hours active-hours + 0.5 set color yellow ] [ ; switch from stasis to feeding ; Note that feeding takes preference over resting if they are tied. ifelse fitness-if-rest > fitness-if-feed [ ; switch from stasis to resting set activity "resting" move-to one-of rest-patches set color red ] [ ; switch to feeding set activity "feeding" move-to one-of feed-patches set active-hours active-hours + 0.5 set color green ] ] ] ; file-print activity ; file-close end to-report predicted-daily-energy-reserve-with [ an-energy-reserve a-gut-content an-activity] ; Calculated predicted energy reserves at end of the day, assuming limpet ; alternates between feeding and stasis for remaining favorable time steps ; and rests remaining unfavorable steps ; Prediction is for time steps *after* the current one. ; "an-energy-reserve" is energy reserve at *end* of current time step ; "a-gut-content" is gut content at *end* of current time step ; Test output file. let test-out? false if test-out? [ file-close-all if first-pred-energy-output? [ if file-exists? "predict-energy-test-V2.csv" [ file-delete "predict-energy-test-V2.csv" ] file-open "predict-energy-test-V2.csv" file-type "tick,favorable?,energy-reserve,gut-content,steps-fav,steps-unfav," file-print "predicted-activity,predicted-energy,predicted-gut,daily-survival" file-close set first-pred-energy-output? false ] file-open "predict-energy-test-V2.csv" ] ; First calculate the number of favorable and unfavorable time steps left, ; not including the current step let steps-fav ifelse-value favorable? [ (2 * (favorable-phase-length - time)) - 1 ] [ 0 ] let steps-unfav ifelse-value favorable? [ 2 * (24 - favorable-phase-length) ] [ (2 * (24 - time)) - 1 ] ; If there are no more time steps, then the current energy reserve is the day's end value if steps-unfav < 0.5 [ report an-energy-reserve ] ; Calculate energy reserve and gut content at start of remaining unfavorable steps let predicted-gut a-gut-content let predicted-energy an-energy-reserve let predicted-activity an-activity let energy-list (list predicted-energy) ; create a list of energy reserves on each remaining time step let went-to-zero? false ; This keeps track of whether energy ever goes to zero ; Calculate energy reserve and gut contents and survival over remaining favorable steps ; We must use iteration to enforce the maximum energy reserve, gut contents, and processing rates repeat steps-fav [ if predicted-activity != "resting" [ set predicted-activity ifelse-value (predicted-gut < (max-gut-content - gut-process-rate)) [ "feeding" ] [ "stasis" ] ] set predicted-energy (new-energy-with predicted-activity predicted-activity predicted-energy predicted-gut) set predicted-gut (gut-content-with predicted-activity predicted-gut) set daily-survival daily-survival * (survival-with predicted-activity true) if predicted-energy < 0.0 [ set went-to-zero? true ] if test-out? [ file-print (word ticks "," favorable? "," an-energy-reserve "," a-gut-content "," steps-fav "," steps-unfav "," predicted-activity "," predicted-energy "," predicted-gut "," daily-survival) ] set energy-list lput predicted-energy energy-list ; add energy to the list ] ; Calculate energy reserve and gut contents at end of unfavorable steps repeat steps-unfav [ set predicted-energy (new-energy-with predicted-activity "resting" predicted-energy predicted-gut) set predicted-activity "resting" set predicted-gut (gut-content-with "resting" predicted-gut) set daily-survival daily-survival * (survival-with predicted-activity false) if predicted-energy < 0.0 [ set went-to-zero? true ] if test-out? [ file-print (word ticks "," favorable? "," an-energy-reserve "," a-gut-content "," steps-fav "," steps-unfav "," predicted-activity "," predicted-energy "," predicted-gut "," daily-survival) ] set energy-list lput predicted-energy energy-list ; add energy to the list ] if test-out? [ file-close ] report ifelse-value went-to-zero? [ 0.0 ] [ mean energy-list ] end ;to-report predicted-survival ; ; Calculated predicted probability of surviving from the next time step to end of the day, assuming limpet ; ; feeds for remaining favorable time steps and rests remaining unfavorable steps ; ; ; First calculate the number of favorable and unfavorable time steps left, ; ; not including the current step ; let steps-fav ifelse-value favorable? ; [ (2 * (favorable-phase-length - time)) - 1 ] ; [ 0 ] ; ; let steps-unfav ifelse-value favorable? ; [ 2 * (24 - favorable-phase-length) ] ; [ (2 * (24 - time)) - 1 ] ; ; report (survival-if-active ^ steps-fav) * (survival-if-rest ^ steps-unfav) ; ;end to-report new-energy-with [current-activity next-activity current-energy current-gut] ; turtle (or global) reporter to calculate energy status for one time step let food-processed current-gut if food-processed > gut-process-rate [ set food-processed gut-process-rate ] let new-energy 0.0 if current-activity = "feeding" or current-activity = "stasis" [ if next-activity = "feeding" [ ;show (word "current-energy: " current-energy "cost: " cost-feeding " energy content: " food-energy " food: " food-processed) set new-energy current-energy - cost-feeding + (food-energy * food-processed) if new-energy > max-energy-reserve [ set new-energy max-energy-reserve ] report new-energy ] if next-activity = "resting" [ set new-energy current-energy - cost-start-resting + (food-energy * food-processed) if new-energy > max-energy-reserve [ set new-energy max-energy-reserve ] report new-energy ] if next-activity = "stasis" [ set new-energy current-energy - cost-stasis + (food-energy * food-processed) if new-energy > max-energy-reserve [ set new-energy max-energy-reserve ] report new-energy ] error (word "In new-energy-with, illegal next activity: " next-activity) ] if current-activity = "resting" [ if next-activity = "feeding" [ set new-energy current-energy - cost-feeding + (food-energy * food-processed) if new-energy > max-energy-reserve [ set new-energy max-energy-reserve ] report new-energy ] if next-activity = "resting" [ set new-energy current-energy - cost-resting + (food-energy * food-processed) if new-energy > max-energy-reserve [ set new-energy max-energy-reserve ] report new-energy ] error (word "In new-energy-with, illegal next activity: " next-activity) ] error (word "In new-energy-with, illegal current activity: " current-activity) end to-report gut-content-with [ next-activity current-gut ] ; turtle (or global) reporter to calculate gut status for one time step let food-processed current-gut if current-gut > gut-process-rate [ set food-processed gut-process-rate ] let new-gut current-gut - food-processed if next-activity = "feeding" [ set new-gut new-gut + ingestion ] if new-gut > max-gut-content [ set new-gut max-gut-content ] report new-gut end to-report survival-with [ an-activity a-favorable? ] ; A turtle (or global) procedure to calculate survival probabilty if an-activity = "resting" [ report survival-if-rest ] if an-activity = "feeding" or an-activity = "stasis" [ ifelse a-favorable? [ report survival-if-active ] [ report survival-if-active-unfavorable ] ] error (word "In survival, illegal activity: " an-activity) end to update-output set-current-plot "Mean limpet status" set-current-plot-pen "Energy" plot (mean [energy-reserves] of limpets) / max-energy-reserve set-current-plot-pen "Gut" plot (mean [gut-content] of limpets) / max-gut-content if file-output? [ if ticks = 1 [ if file-exists? "Limpet-output.csv" [file-delete "Limpet-output.csv"] file-open "Limpet-output.csv" file-print "tick,time,limpet,favorable?,activity,energy-reserves,gut-content" file-close ] file-open "Limpet-output.csv" ask limpets [ file-print (word ticks "," time "," who "," favorable? "," activity "," energy-reserves "," gut-content) ] file-close ] end @#$#@#$#@ GRAPHICS-WINDOW 210 10 335 344 -1 -1 13.0 1 10 1 1 1 0 1 1 1 -4 4 -12 12 0 0 1 ticks 30.0 BUTTON 13 11 76 44 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL 1 SLIDER 11 117 190 150 favorable-phase-length favorable-phase-length 0 24 10.0 1 1 hours HORIZONTAL BUTTON 84 11 147 44 NIL go T 1 T OBSERVER NIL NIL NIL NIL 1 BUTTON 85 48 148 81 step go NIL 1 T OBSERVER NIL NIL NIL NIL 1 PLOT 349 10 629 219 Mean limpet status Tick Fraction of maximum 0.0 1.0 0.0 1.0 true true "" "" PENS "Energy" 1.0 0 -16777216 true "" "" "Gut" 1.0 0 -10899396 true "" "" SWITCH 11 156 130 189 file-output? file-output? 1 1 -1000 @#$#@#$#@ # Limpet Foraging Model This code is provided to support the book "Modeling Populations of Adaptive Individuals" by Railsback and Harvey. It implements version 3 of the the limpet foraging model described in Section 6.5. The simulated limpet selects its activity by maximizing mean expected energy reserves until the end of the current day. The code was developed in NetLogo version 6.0.2 but should work in subsequent versions. The model is controlled and observed from the "Interface" tab. The program statements are on the "Code" tab; click the "Procedures" button to see a list of all the procedures (subroutines) in the code and go to one. The model simulates one limpet over 8 days, with time steps of 1/2 hour. ## Executing the model from the Interface 1. Click on the "setup" button to initialize the model. (This executes the "setup" procedure.) 2. Click on the "go" button to execute a complete simulation. Use the speed slider at the top of the Interface to slow down execution so it can be observed. (This button executes the "go" procedure, the model's schedule, repeatedly for the selected number of time steps.) 3. The "step" button executes just one time step each time it is clicked. 4. The above steps can be repeated as desired. ## Interface elements The Interface provides the following displays and controls, in addition to the setup, go, and step buttons described above. * The "view" (large rectangle that says "Ticks:" at the top) is configured simply to display the model state, as the model is non-spatial. After "setup" is executed, the view displays the following.You can right-click on the simulated limpet to open an "inspector" that displays all state variables. * The limpet is displayed as a circle. The limpet is red when using resting activity, yellow when using stasis, and green when feeding. * When the limpet is active (feeding or stasis) it is in the upper grey part of the space; when resting, it is in the lower blue area. * An arrow at the upper right displays the current simulate time; it acts as the hour hand of a 12-hour clock, pointing up at 12 and down at 6. The arrow is yellow during the first 12 hours of the day and black in the second 12 hours. * The plot "Mean limpet status" graphs time series of the limpet's gut content and energy reserves, both as a fraction (0-1) of their maximum values. The X axis is the number of time steps, which is two times the number of hours simulated. If multiple limpets are simulated, this plot displays the mean values over all limpets. * The "favorable-phase-length" slider controls the number of hours per day with "favorable" feeding conditions. It can be changed before or during a simulation. * When the "file-output?" switch is on, an output file is written each time the model is run. This switch must be set before the "setup" button is used to initialize a model run. The file is called "LimpetOutput.csv" and is overwritten each time the model runs. The file reports the selected activity, gut contents, and energy reserves of each limpet, at the end of each time step. (If the model generates an error statement when "go" or "step" are clicked on, it is often because this output file was left open in another program.) **This option is not available in the web version of the model.** ## Version control Last modified 16 July 2018 SF Railsback Re-named and Info tab updated 7 August 2018 SF Railsback @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 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face neutral false 0 Circle -7500403 true true 8 7 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Rectangle -16777216 true false 60 195 240 225 face sad false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183 fish false 0 Polygon -1 true false 44 131 21 87 15 86 0 120 15 150 0 180 13 214 20 212 45 166 Polygon -1 true false 135 195 119 235 95 218 76 210 46 204 60 165 Polygon -1 true false 75 45 83 77 71 103 86 114 166 78 135 60 Polygon -7500403 true true 30 136 151 77 226 81 280 119 292 146 292 160 287 170 270 195 195 210 151 212 30 166 Circle -16777216 true false 215 106 30 flag false 0 Rectangle -7500403 true true 60 15 75 300 Polygon -7500403 true true 90 150 270 90 90 30 Line -7500403 true 75 135 90 135 Line -7500403 true 75 45 90 45 flower false 0 Polygon 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120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195 Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195 line true 0 Line -7500403 true 150 0 150 300 line half true 0 Line -7500403 true 150 0 150 150 pentagon false 0 Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120 person false 0 Circle -7500403 true true 110 5 80 Polygon -7500403 true true 105 90 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 195 90 Rectangle -7500403 true true 127 79 172 94 Polygon -7500403 true true 195 90 240 150 225 180 165 105 Polygon -7500403 true true 105 90 60 150 75 180 135 105 plant false 0 Rectangle -7500403 true true 135 90 165 300 Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285 Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285 Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210 Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135 Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135 Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60 Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90 sheep false 15 Circle -1 true true 203 65 88 Circle -1 true true 70 65 162 Circle -1 true true 150 105 120 Polygon -7500403 true false 218 120 240 165 255 165 278 120 Circle -7500403 true false 214 72 67 Rectangle -1 true true 164 223 179 298 Polygon -1 true true 45 285 30 285 30 240 15 195 45 210 Circle -1 true true 3 83 150 Rectangle -1 true true 65 221 80 296 Polygon -1 true true 195 285 210 285 210 240 240 210 195 210 Polygon -7500403 true false 276 85 285 105 302 99 294 83 Polygon -7500403 true false 219 85 210 105 193 99 201 83 square false 0 Rectangle -7500403 true true 30 30 270 270 square 2 false 0 Rectangle -7500403 true true 30 30 270 270 Rectangle -16777216 true false 60 60 240 240 star false 0 Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108 target false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 Circle -7500403 true true 60 60 180 Circle -16777216 true false 90 90 120 Circle -7500403 true true 120 120 60 tree false 0 Circle -7500403 true true 118 3 94 Rectangle -6459832 true false 120 195 180 300 Circle -7500403 true true 65 21 108 Circle -7500403 true true 116 41 127 Circle -7500403 true true 45 90 120 Circle -7500403 true true 104 74 152 triangle false 0 Polygon -7500403 true true 150 30 15 255 285 255 triangle 2 false 0 Polygon -7500403 true true 150 30 15 255 285 255 Polygon -16777216 true false 151 99 225 223 75 224 truck false 0 Rectangle -7500403 true true 4 45 195 187 Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194 Rectangle -1 true false 195 60 195 105 Polygon -16777216 true false 238 112 252 141 219 141 218 112 Circle -16777216 true false 234 174 42 Rectangle -7500403 true true 181 185 214 194 Circle -16777216 true false 144 174 42 Circle -16777216 true false 24 174 42 Circle -7500403 false true 24 174 42 Circle -7500403 false true 144 174 42 Circle -7500403 false true 234 174 42 turtle true 0 Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210 Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105 Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105 Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87 Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210 Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99 wheel false 0 Circle -7500403 true true 3 3 294 Circle -16777216 true false 30 30 240 Line -7500403 true 150 285 150 15 Line -7500403 true 15 150 285 150 Circle -7500403 true true 120 120 60 Line -7500403 true 216 40 79 269 Line -7500403 true 40 84 269 221 Line -7500403 true 40 216 269 79 Line -7500403 true 84 40 221 269 wolf false 0 Polygon -16777216 true false 253 133 245 131 245 133 Polygon -7500403 true true 2 194 13 197 30 191 38 193 38 205 20 226 20 257 27 265 38 266 40 260 31 253 31 230 60 206 68 198 75 209 66 228 65 243 82 261 84 268 100 267 103 261 77 239 79 231 100 207 98 196 119 201 143 202 160 195 166 210 172 213 173 238 167 251 160 248 154 265 169 264 178 247 186 240 198 260 200 271 217 271 219 262 207 258 195 230 192 198 210 184 227 164 242 144 259 145 284 151 277 141 293 140 299 134 297 127 273 119 270 105 Polygon -7500403 true true -1 195 14 180 36 166 40 153 53 140 82 131 134 133 159 126 188 115 227 108 236 102 238 98 268 86 269 92 281 87 269 103 269 113 x false 0 Polygon -7500403 true true 270 75 225 30 30 225 75 270 Polygon -7500403 true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 6.0.2 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ setup go mean [active-hours] of limpets / 8 @#$#@#$#@ @#$#@#$#@ default 0.0 -0.2 0 0.0 1.0 0.0 1 1.0 0.0 0.2 0 0.0 1.0 link direction true 0 Line -7500403 true 150 150 90 180 Line -7500403 true 150 150 210 180 @#$#@#$#@ 0 @#$#@#$#@