Basic Income - Individuals

globals
[
  gini-index-reserve
  lorenz-points
  max-wealth
  min-wealth
  max-income
  min-income
  monthly-bi
  max-indiv-cost-of-living
]

patches-own
[
  patch-income      ;; the current amount of income on this patch
  monthly-income
]

turtles-own
[
  wealth    ;; the amount of money a turtle has
  after-tax ;; amount of income left after paying taxes
  min-indiv-cost-of-living ;; individual minimum cost of living based on minimum set on interface
]

;;;
;;; SETUP AND HELPERS
;;;

to setup
  clear-all
  ;; call other procedures to set up various parts of the world
  setup-patches
  setup-turtles
  update-lorenz-and-gini
  reset-ticks
end 

;; set up the initial amounts of income each patch has

to setup-patches
  ;; set up patch income random amount between 0 and upper limit of income
  ;; set colour so richer patches have darker colour (in quintiles)
  ask patches
    [ if income-distribution = "random"
      [
        set patch-income random (mean-annual-income * 2)
      ]
      if income-distribution = "normal"
      [
        set patch-income random-normal  mean-annual-income (mean-annual-income / 2) ;; latter value is an estimate of the standard deviation based on what the curve looks like
      ]
      if income-distribution = "exponential"
      [
        set patch-income random-exponential (mean-annual-income)
      ]
      if patch-income < 0
      [
        set patch-income 0
      ]
      set max-income max [ patch-income ] of patches       ;; find highest income
      if patch-income < max-income * 1 / 5 [ set pcolor 58 ]   ;; colour patches based on income levels
      if patch-income >= max-income * 1 / 5 and patch-income < max-income * 2 / 5 [ set pcolor 57 ]
      if patch-income >= max-income * 2 / 5 and patch-income < max-income * 3 / 5 [ set pcolor 56 ]
      if patch-income >= max-income * 3 / 5 and patch-income < max-income * 4 / 5 [ set pcolor 55 ]
      if patch-income >= max-income * 4 / 5 [ set pcolor 54 ]
  ]
end 

;; set up the initial values for the turtle variables

to setup-turtles
  set-default-shape turtles "person"
  create-turtles num-people
  ask turtles [
    move-to one-of patches with [not any? turtles-here]
    ifelse allow-varied-min-cost-of-living [
    set min-indiv-cost-of-living random-normal min-monthly-cost-of-living (min-monthly-cost-of-living / 6)
      set max-indiv-cost-of-living max [min-indiv-cost-of-living] of turtles ]
    [set min-indiv-cost-of-living min-monthly-cost-of-living]
    if inheritance-distribution = "random"     ;; wealth
    [
      set wealth random (mean-inheritance * 2)
    ]
    if inheritance-distribution = "normal"
    [
      set wealth random-normal mean-inheritance (mean-inheritance / 4) ;; latter value is an estimate of the standard deviation
    ]
    if inheritance-distribution = "exponential"
    [
      set wealth random-exponential (mean-inheritance)
    ]
    if wealth <= 0
    [
      set wealth 1
    ]
    color-turtles
    if inheritance-tax = "flat"                     ;; wealth tax happens once at beginning (if it happens at all)
    [ set wealth wealth * ( 1 - max-tax-rate / 100 ) ]
    if inheritance-tax = "progressive"
    [ if color = 1 [ set wealth wealth * (1 - max-tax-rate / 100) ]
      if color = 2 [ set wealth wealth * (1 - 0.8 * max-tax-rate / 100) ]
      if color = 3 [ set wealth wealth * (1 - 0.6 * max-tax-rate / 100) ]
      if color = 4 [ set wealth wealth * (1 - 0.4 * max-tax-rate / 100) ]
      if color = 5 [ set wealth wealth * (1 - 0.2 * max-tax-rate / 100) ]
    ]
    set monthly-income patch-income / 12
    face one-of neighbors4
  ]
end 

;;;
;;; GO AND HELPERS
;;;

to go
  ask turtles
  [
    upgrade-income   ;; move to neighbouring patch if it has more income
    update-wealth    ;; add net income to wealth
    color-turtles    ;; set colour according to wealth quintile
  ]
  update-lorenz-and-gini
  set min-income min [ patch-income ] of patches
  set min-wealth min [ wealth ] of turtles
  tick
end 

to go-ten-years
  ask turtles
  [
    upgrade-income   ;; move to neighbouring patch if it has more income
    update-wealth    ;; add net income to wealth
    color-turtles    ;; set colour according to wealth quintile
  ]
  update-lorenz-and-gini
  tick
  if ticks = 120
  [
    reset-ticks
    stop
  ]
end 


;; determine the direction which is most profitable for each turtle in
;; the surrounding patches within one patch
;; the only way I could get this to work was to have them just check one direction per tick

to upgrade-income  ;; turtle procedure
  let patch-income-ahead patch-income-at-angle 0
  ;; if patch ahead has a higher income, go to it; and either way, rotate right 90°
  if (patch-income-ahead > patch-income)
  [ if not any? other turtles-on patch-ahead 1
    [ forward 1 ]]
  rt 90
  set monthly-income patch-income / 12
end 

;; check out which neighbouring patch has the highest income (cribbed from ants)

to-report patch-income-at-angle [angle]
  let p patch-right-and-ahead angle 1
  report [patch-income] of p
end 

;; add monthly income to wealth and subtract cost of living; grade cost of living to income if high enough

to update-wealth
  ;; set income tax rate: after-tax = proportion of income left after paying taxes
  if income-tax = "none" [ set after-tax 1 ]
  if income-tax = "flat" [ set after-tax 1 - max-tax-rate / 100 ]
  if income-tax = "progressive with loopholes for rich"
  [ if pcolor = 54 [ set after-tax 1 - 0.6 * (max-tax-rate / 100) ]
    if pcolor = 55 [ set after-tax 1 - 0.8 * (max-tax-rate / 100) ]
    if pcolor = 56 [ set after-tax 1 - 0.6 * (max-tax-rate / 100) ]
    if pcolor = 57 [ set after-tax 1 - 0.4 * (max-tax-rate / 100) ]
    if pcolor = 58 [ set after-tax 1 - 0.2 * (max-tax-rate / 100) ]
  ]
  if income-tax = "progressive no loopholes for rich"
  [ if pcolor = 54 [ set after-tax 1 - 1.0 * (max-tax-rate / 100) ]
    if pcolor = 55 [ set after-tax 1 - 0.8 * (max-tax-rate / 100) ]
    if pcolor = 56 [ set after-tax 1 - 0.6 * (max-tax-rate / 100) ]
    if pcolor = 57 [ set after-tax 1 - 0.4 * (max-tax-rate / 100) ]
    if pcolor = 58 [ set after-tax 1 - 0.2 * (max-tax-rate / 100) ]
  ]
  ;; set redistribution
  if income-redistribution = "none"
  [
    set monthly-bi 0
  ]
  if income-redistribution = "universal demogrant"   ;; give everyone the same top-up
  [
    set monthly-bi max-bi / 12
  ]
  if income-redistribution = "NIT with clawback"   ;; calculate partial BI after clawback
  [
    set monthly-bi max-bi / 12
    ifelse (monthly-income * after-tax * (clawback / 100)) < monthly-bi   ;; is after tax income too high with clawback?, if not proceed
    [
      set monthly-bi monthly-bi - (monthly-income * after-tax * (clawback / 100))
    ]
    ;; for NIT, if after-tax income is too high, don't give a BI
    [
      set monthly-bi 0
    ]
  ]
  ;; calculate new wealth
  ifelse ((monthly-bi + (monthly-income * after-tax)) * 3 / 4) < min-indiv-cost-of-living ;; deduct cost of living
  [set wealth wealth + monthly-bi + (monthly-income * after-tax) - min-indiv-cost-of-living ]
  [set wealth wealth + monthly-bi + (monthly-income * after-tax / 4) ]
end 

to color-turtles
  set max-wealth  max [ wealth ] of turtles
    if wealth < max-wealth / 5
    [ set color 5 ]
    if (wealth >= max-wealth / 5 and wealth < max-wealth * 2 / 5)
    [ set color 4 ]
    if (wealth >= max-wealth * 2 / 5 and wealth < max-wealth * 3 / 5)
    [ set color 3 ]
    if (wealth >= max-wealth * 3 / 5 and wealth < max-wealth * 4 / 5)
    [ set color 2 ]
    if (wealth >= max-wealth * 4 / 5)
    [ set color 1 ]
    if wealth <= 0
    [ set wealth 1
      set color red
    ]
end 

;; this procedure recomputes the value of gini-index-reserve
;; and the points in lorenz-points for the Lorenz and Gini-Index plots

to update-lorenz-and-gini
    let sorted-wealths sort [wealth] of turtles
  let total-wealth sum sorted-wealths
  let wealth-sum-so-far 0
  let index 0
  set gini-index-reserve 0
  set lorenz-points []

  ;; now actually plot the Lorenz curve -- along the way, we also
  ;; calculate the Gini index.
  ;; (see the Info tab for a description of the curve and measure)
  repeat count turtles [
    set wealth-sum-so-far (wealth-sum-so-far + item index sorted-wealths)
    set lorenz-points lput ((wealth-sum-so-far / total-wealth) * 100) lorenz-points
    set index (index + 1)
    set gini-index-reserve
      gini-index-reserve +
      (index / num-people) -
      (wealth-sum-so-far / total-wealth)
  ]
end 


; Copyright 1998 Uri Wilensky and 2018 Sarah Robertson
; See Info tab for full copyright and license.