# Baby-sitting co-op

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;; A parameterized model of the Capital Hill Baby-Sitting Co-op ;; Copyright (C) 2015 Russ Abbott ;; ;; This program is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation; either version 2 of the License, or ;; (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, but ;; WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ;; General Public License (http://www.gnu.org/licenses/) for more details. turtles-own [ scrip scrip-needed want-sitter? want-to-go-out? enough-scrip? going-out? want-to-sit? sitting? ] globals [ aggregated-hours-out cycle-pos frustrated-want-sitter frustrated-want-to-sit going-out# max-gini max-scrip my-ticks no-sitter# no-sitting-jobs# not-enough-scrip# quiet-evening# sitting# sitting-as-1st-choice# sitting-as-2nd-choice# stop-run? total-hours-out total-scrip want-sitter# want-to-go-out# want-to-sit# ] extensions [ array table ] ;;;;;;;;;;;;;;;;;;;;; to setup clear-all create-co-op set aggregated-hours-out table:make set total-hours-out 0 set max-scrip 0 ;; set monthly-dues 1 set frustrated-want-sitter no-turtles set frustrated-want-to-sit no-turtles set stop-run? false reset-ticks end ;;;;;;;;;;;;;;;;;;;;; to go reset-turtles ;; my-ticks is used as a settable proxy for ticks for testing set my-ticks ticks set cycle-pos (sin ( my-ticks mod 360 )) * cycle-amplitude ;; Uses a 360 day year. plan-evening match-sitees-and-sitters if clear-sitter-market? [ clear-sitter-market ] check-consistency set total-scrip sum [scrip] of turtles let max-scrip-now max [scrip] of turtles set max-scrip ceiling maxi max-scrip max-scrip-now ;; a gross approximation of the GINI constant. It is always very low and not very useful let gini ifelse-value (total-scrip = 0) [0] [(max-scrip-now / total-scrip) - (1 / co-op-size)] set max-gini maxi max-gini gini tick ;; should the central bank adjust the monthy dues? if auto-adjust [ set-monthly-dues ] if ticks mod 12 = 0 [ ask turtles [ set scrip scrip - monthly-dues ] ] ;; stop-run is set to true if an internal inconsistency is noticed if ticks >= 365 * years or stop-run? [stop] end ;;;;;;;;;;;;;;;;;;;;; ;; Performs no model function. Checks the consistency of the values computed. ;; Essentially a continual regression test. to check-consistency set frustrated-want-sitter turtles with [ want-sitter? and not going-out? and not sitting? ] set frustrated-want-to-sit turtles with [ want-to-sit? and not sitting? ] if count frustrated-want-sitter > 0 and count frustrated-want-to-sit > 0 [ show word "No sitters: " frustrated-want-sitter show word "Available sitters: " frustrated-want-to-sit set stop-run? true ] set want-sitter# count turtles with [want-sitter?] set want-to-sit# count turtles with [want-to-sit?] set quiet-evening# count turtles with [not want-sitter? and not want-to-sit?] if want-sitter# + want-to-sit# + quiet-evening# != co-op-size [ show "want-sitter# + want-to-sit# + quiet-evening# != co-op-size failed" set stop-run? true ] set want-to-go-out# count turtles with [want-to-go-out?] set not-enough-scrip# count turtles with [want-to-go-out? and not enough-scrip?] if want-sitter# + not-enough-scrip# != want-to-go-out# [ show "want-sitter# + not-enough-scrip# != want-to-go-out# failed" set stop-run? true ] set going-out# count turtles with [ going-out? ] set no-sitter# count frustrated-want-sitter set sitting-as-2nd-choice# count turtles with [ want-sitter? and sitting? ] if going-out# + no-sitter# + sitting-as-2nd-choice# != want-sitter# [ show "want-to-go-out# - not-enough-scrip# != want-sitter# failed" set stop-run? true ] set sitting-as-1st-choice# count turtles with [ want-to-sit? and sitting? ] set no-sitting-jobs# count frustrated-want-to-sit if sitting-as-1st-choice# + no-sitting-jobs# != want-to-sit# [ show "sitting-as-first-choice# + no-sitting-jobs# != want-to-sit# failed" set stop-run? true ] set sitting# count turtles with [ sitting? ] if not multiple-sitees? and going-out# != sitting# [ show "going-out# = sitting# failed" set stop-run? true ] end ;; If more members want to go out than sit, the extras sit for each other if they are willing. to clear-sitter-market ;; Don't look at turtles that just want-to-go-out. They may not have enough scrip, ;; in which case they were already asked if they want to sit. ;; uncleared-turtles are those who can't find sitters through the first step of the planning process. let uncleared-turtles turtles with [ want-sitter? and not going-out? ] ;; sitters-set are willing to sit let sitters-set uncleared-turtles with [ random-probability < willing-to-sit? ] ;; sittees is a list unwilling to sit let sittees [ self ] of uncleared-turtles with [ not member? self sitters-set ] ;; sitters is a list willing to sit. It's just a copy of sitter-set. let sitters [ self ] of sitters-set ;; [self] ofturns the AgentSet into a List if-else length sitters > length sittees [ set sitters n-of length sittees sitters ] [ set sittees n-of length sitters sittees ] (foreach sittees sitters [ pay-sitter ?1 ?2 "clear-sitters1" ] ) ;; Any sitters left over can sit for each other. let extra-sitters [ self ] of sitters-set with [ not sitting? ] set sittees n-of ((length extra-sitters) / 2) extra-sitters set sitters n-of length sittees filter [not member? ? sittees] extra-sitters (foreach sittees sitters [ pay-sitter ?1 ?2 "clear-sitters2" ] ) end to create-co-op create-turtles co-op-size [ set scrip initial-scrip set hidden? true ] reset-turtles end ;; Determine the time this member will go out this day. to-report get-event-length if random-probability > get-want-to-go-out-probability [ report 0 ] if hours-out-distribution = "uniform" [ report (random (mean-hours-out + mean-hours-out / 2)) + 1 ] if hours-out-distribution = "poisson" [ report (random-poisson (mean-hours-out - 1)) + 1 ] if hours-out-distribution = "none" [ report mean-hours-out ] end ;; Determine the probability that this member wants to go out to-report get-want-to-go-out-probability report seasonally-adjusted-prob (mini percent-of-desired-times-out-reserve want-to-go-out-probability) cycle-pos end ;; Determine the probability that this member wants to sit to-report get-want-to-sit-probability report seasonally-adjusted-prob (maxi (1 - percent-of-desired-times-out-reserve) want-to-sit-probability) ((-1) * cycle-pos) end ;; Used to keep track of the distribution of event lengths to increment-table [ table instance ] let current-value ifelse-value table:has-key? table instance [table:get table instance] [0] table:put table instance current-value + 1 end ;; By this time the members have want-sitter or want-to-sit set of they want to go out or want to sit to match-sitees-and-sitters let want-sitters [self] of turtles with [ want-sitter? ] let available-sitters [self] of turtles with [ want-to-sit? ] if length want-sitters < length available-sitters [ set available-sitters n-of length want-sitters available-sitters ] if length want-sitters > length available-sitters [ if-else multiple-sitees? and length available-sitters > 0 [ set available-sitters repeat-to available-sitters length want-sitters ] [ set want-sitters n-of length available-sitters want-sitters ] ] ( foreach want-sitters available-sitters [ pay-sitter ?1 ?2 "match-sitees-and-sitters" ] ) end ;; max with 2 parameters to-report maxi [a b] report max list a b end ;; min with 2 parameters to-report mini [a b] report min list a b end ;; transfer scrip from sittee to sitter. to pay-sitter [sittee sitter source] if [going-out?] of sittee [ show (sentence source " " sittee " sittee going out twice") set stop-run? true ] if [sitting?] of sittee [ show (sentence source " " sittee " sittee already sitting") set stop-run? true] if [going-out?] of sitter [ show (sentence source " " sitter " sitter already going out") set stop-run? true ] if not multiple-sitees? and [sitting?] of sitter [ show (sentence source " " sitter " sitter sitting twice ") set stop-run? true ] let payment [scrip-needed] of sittee ask sittee [ set scrip scrip - payment set going-out? true ] ask sitter [ set scrip scrip + payment set sitting? true set total-hours-out total-hours-out + payment ] end ;; Append the list xs to itself until the total length is = n to-report repeat-to [xs n] if-else length xs < n [ report repeat-to sentence xs xs n ] [ report n-of n xs ] end ;; Returns the percent of the desired times-out reserve this member has in scrip ;; The desired times-out reserve is the number of times the member can afford to ;; go out without additional sitting to-report percent-of-desired-times-out-reserve report ifelse-value (desired-times-out-reserve = 0) [ 1 ] ; ifelse-value (scrip <= 0) [0] [1] ; ] [ percent-of-limit scrip mean-hours-out * desired-times-out-reserve ] ;;[ mini 1 maxi 0 ( scrip / ( mean-hours-out * desired-times-out-reserve ) ) ] end ;; Amount is what percent of limit. Constrain result to be between 0 and 1. to-report percent-of-limit [amount limit] report mini 1 maxi 0 ( amount / limit ) end ;; Determine what, if anything each member wants to do and set their flags accordingly to plan-evening ask turtles [ let hours-out-wanted get-event-length if hours-out-wanted > 0 [ increment-table aggregated-hours-out hours-out-wanted ] ;; In this model each unit of scrip buys a full hour of sitting. In the original ;; each unit bought half an hour. set scrip-needed hours-out-wanted ;; scrip-needed = 0 indicates that the member doesn't want to go out. if scrip-needed > 0 [ set want-to-go-out? true ;; can go out only if member posesses enough scrip if scrip >= scrip-needed [ set want-sitter? true set enough-scrip? true ] ] ;; Member who don't want to go out or don't have enough scrip are asked if they want to sit. set want-to-sit? not want-sitter? and random-probability < get-want-to-sit-probability ] end ;; Plots the hours-out histogram to plot-table-as-percentages [tab] let pct-list table-as-pct-list tab if length pct-list > 0 [ plot-pen-reset ;; erase what we plotted before let keys table:keys tab set-plot-x-range min keys - 1 (max keys + 1) set-plot-y-range 0 ceiling max pct-list + 1 ;; Not clear why fput 0 is needed. If not done, first value is not plotted. ;; With it, the extra initial zero is not plotted. foreach fput 0 pct-list plot ] end ;; All NetLogo arithmetic is done if floating point. to-report random-probability report (random 100) / 100 end ;; Unset all flags to reset-turtles ask turtles [ set going-out? false set enough-scrip? false set sitting? false set want-sitter? false set want-to-go-out? false set want-to-sit? false ] end ;; Adjust want-to-go-out and want-to-sit for the season. ;; If aren't using seasons, cycle-p will be 0 and no change will occur. ;; Otherwise increase toward 1 or decrease toward 0 the input probability ;; based on the cycle value. to-report seasonally-adjusted-prob [p cycle-p] let diff ifelse-value (cycle-p > 0) [1 - p] [ ifelse-value (cycle-p = 0) [0] [p]] report p + diff * cycle-p end ;; Sets the monthly dues to control the money supply to set-monthly-dues if no-sitting-jobs# > max-no-sitting [set monthly-dues -0.3] if no-sitting-jobs# < min-no-sitting [set monthly-dues 0.6] end ;; Converts a table into an array of percentages to make a histogram. ;; Requires that the keys of the table be integers. ;; They become the indices of an array in which the corresponding values are stored ;; Then a list is created and returned with each value replaced by its pct (0 to 100) of the sum of all values to-report table-as-pct-list [tab] let keys table:keys tab ;; The keys are the indices of the array/list (zero-based). (max keys) is the index of the last element. if length keys = 0 [ report [ ] ] let min-key min keys let arr array:from-list n-values (1 + max keys - min-key) [0] foreach keys [array:set arr (? - min-key) table:get tab ?] let list-arr array:to-list arr let sum-of-elements sum list-arr ;; Compute the sum only once report map [ round ( 100 * ? / sum-of-elements ) ] list-arr end

There is only one version of this model, created over 5 years ago by Russ Abbott.

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