# Child of COVID_19 Spread

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turtles-own [ sick? ;; if true, the turtle is infectious remaining-immunity ;; how many weeks of immunity the turtle has left sick-time ;; how long, in days, the turtle has been infectious age ;; how many weeks old the turtle is quarentine? ;; if true the turtle is in quarentine ] globals [ %infected ;; what % of the population is infectious %immune ;; what % of the population is immune lifespan ;; the lifespan of a turtle chance-reproduce ;; the probability of a turtle generating an offspring each tick chance-recover ;; the probability of recovery at each tick carrying-capacity ;; the number of turtles that can be in the world at one time immunity-duration ;; how many weeks immunity lasts number-dead ] ;; how many turtles die ;; The setup is divided into four procedures to setup clear-all setup-constants setup-turtles update-global-variables update-display reset-ticks end ;; We create a variable number of turtles of which 1 are infectious, ;; and distribute them randomly to setup-turtles create-turtles number-people [ setxy random-xcor random-ycor set age random lifespan set sick-time 0 set remaining-immunity 0 set size .7 ;; easier to see get-healthy set quarentine? false ] ask n-of ((accepted-quarentine * number-people) / 100) turtles [set quarentine? call-for-quarentine] ask n-of 1 turtles [ get-sick pen-down ] end to get-sick ;; turtle procedure set sick? true pen-down set remaining-immunity 0 end to get-healthy ;; turtle procedure set sick? false set remaining-immunity 0 set sick-time 0 end to become-immune ;; turtle procedure set sick? false set sick-time 0 set remaining-immunity immunity-duration ask my-links [ die ] ;; remove link to turtle who infected us, if there was one end ;; This sets up basic constants of the model. to setup-constants set lifespan 80 * 52 * 7 ;; 80 times 52 weeks times 7 days = 50 years = 2600 weeks old = 18200 days set carrying-capacity 1089 set chance-reproduce 0.34 ;; birth rate per 1000 people per week set immunity-duration 4 * 7 ;; 4 weeks for immunity duration if Weather = "Hot-Humid" [set infectiousness .9 * infectiousness] if Weather = "Hot-Dry" [set infectiousness .95 * infectiousness] if Weather = "Cold-Dry" [set infectiousness .97 * infectiousness] if Weather = "Cold-Humid" [set infectiousness infectiousness] end to go ask turtles [ get-older if not quarentine? [move] if sick? [ recover-or-die ] ifelse sick? [ infect ] [ reproduce ] ] update-global-variables update-display tick if ticks = 100 [stop] ;; here ask for call-for-quarentine ;; if quarentine colour patch with red and inmovilize turtle if call-for-quarentine [ ask turtles with [quarentine? = true] [ ask patch pxcor pycor [set pcolor red] ] ] end to update-global-variables if count turtles > 0 [ set %infected (count turtles with [ sick? ] / count turtles) * 100 set %immune (count turtles with [ immune? ] / count turtles) * 100 ] end to update-display ask turtles [ if shape != turtle-shape [ set shape turtle-shape ] set label ifelse-value show-age? [ floor (age / 364) ] [ "" ] set color ifelse-value sick? [ red ] [ ifelse-value immune? [ grey ] [ green ] ] ;; not showing colour by age ;if age < 10 * 52 * 7 [set color blue] ;if age > 60 * 52 * 7 [set color yellow] ] stop-inspecting-dead-agents if watch-a-person? and subject = nobody [ watch one-of turtles with [ not hidden? ] clear-drawing ask subject [ pen-down ] inspect subject ] if not watch-a-person? and subject != nobody [ stop-inspecting subject ask subject [ pen-up ask my-links [ die ] ] clear-drawing reset-perspective ] ask patches [ if Weather = "Hot-Humid" [set pcolor 68] if Weather = "Hot-Dry" [set pcolor 48] if Weather = "Cold-Dry" [set pcolor 38] if Weather = "Cold-Humid" [set pcolor 108] ] end ;;Turtle counting variables are advanced. to get-older ;; turtle procedure ;; Turtles die of old age once their age exceeds the ;; lifespan (set at 80 years in this model). set age age + 1 if age > lifespan [ die ] if age > 60 * 52 * 7 [ set chance-recover .93] if age < 60 * 52 * 7 [ set chance-recover .97] if immune? [ set remaining-immunity remaining-immunity - 1 ] if sick? [ set sick-time sick-time + 1 ] end ;; Turtles move about at random. to move ;; turtle procedure rt random 100 lt random 100 fd movement end ;; If a turtle is sick, it infects other turtles on the same patch. ;; Immune turtles don't get sick. to infect ;; turtle procedure ask other turtles-here with [ not sick? and not immune? and not quarentine?] [ if random-float 100 < infectiousness [ get-sick if self = subject ;; if its the watched turtle getting sick [ create-link-with myself ;; create a link with the one that infected it [ set color red set thickness .3 ] ] ] ] end ;; Once the turtle has been sick long enough, it ;; either recovers (and becomes immune) or it dies. to recover-or-die ;; turtle procedure if age > 60 * 52 * 7 [ set chance-recover .93] if age < 60 * 52 * 7 [ set chance-recover .97] if sick-time > duration ;; If the turtle has survived past the virus' duration, then [ ifelse random-float 100 < chance-recover ;; either recover or die [ become-immune ] [ set number-dead number-dead + 1 die ]] end ;; If there are less turtles than the carrying-capacity ;; then turtles can reproduce. to reproduce if count turtles < carrying-capacity and random-float 100 < chance-reproduce [ hatch 1 [ set age 1 lt 45 fd 1 pen-up ;; in case we're hatched from the watched turtle get-healthy ] ] end to-report immune? report remaining-immunity > 0 end to startup setup-constants ;; so that carrying-capacity can be used as upper bound of number-people slider end ; Copyright 1998 Uri Wilensky. ; See Info tab for full copyright and license.

There is only one version of this model, created almost 4 years ago by Facundo Parra.

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**Parent:** COVID_19 Spread

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