Flibs'NFarol

;;  _________________________________________________________________________________________________________________
;;
;;  --------------------   FlibsN'Farol   ---------------------------------------------------------   FlibsN'Farol
;;  FlibsN'Farol   ---------------------------------------------------------   FlibsN'Farol   -----------------------
;;  _________________________________________________________________________________________________________________



breed     [flibs flib]     ;; FLiBs (finite living blobs) are the agents of the model: they are structured as
                           ;; finite automata. They have "a finite number of states; an input signal
                           ;; causes it to change automatically from one state to another. The kind of automaton
                           ;; used in a flib also generates signals. Incoming and outgoing signals are represented
                           ;; within the automaton by symbols. When a signal is received, the automaton changes
                           ;; state and emits a second signal" (A. K. Dewdney, 1985)


flibs-own [chromosome      ;; every flib owns a chromosome, that is a string codifying its state transitions schema
           state           ;; the current inner state of the flib
           choice          ;; choice/prevision expressed by the flib regarding to go or not to go to the bar
           fitness         ;; a measure of flibs' prevision ability to forestall if the bar will be crowded or not
           ]


globals  [tot_attend        ;; total of attendances during one season to "El Farol" bar (i.e. 100 cycles tournement)
          sigma_attend      ;; an accumulator for the previous variable
          crowded           ;; a switch recording the state of the bar: 1 if overcrowded, 0 if not
          lorenz-points     ;; list of the Lorenz curve ordinates
          gini-index-reserve;; counter functional to the calculation of the Gini index
          sigma-gini        ;; an accumulator for the previous variable
          diversity         ;; the number of the different chromosomes in the flibs population
          sigma_divers      ;; an accumulator for the previous variable
          best              ;; the best flibs fitness value
          worst             ;; the worst flibs fitness value
          donor             ;; one of best-performing flibs sharing part of its genes
          recipient         ;; one flib acquiring genes from the donor flib
          a-split           ;; the first cut in the recipient's chromosome
          b-split           ;; the second cut in the recipient's chromosome
          locus             ;; pointer/counter of chromosome loci
          ]


;;  ----------   SETUP PROCEDURES   ----------------------------------------------------------------------------------
;;  ------------------------------------------------------------------------------------------------------------------

to setup           ;; initializing the model
  clear-all
  ;; create the bar area (yellow) and an elsewhere (blue)
  ask patches  [set pcolor blue - 3]
  ask patches with [abs pxcor < 10 and abs pycor < 7] [set pcolor yellow]
  ask patches with [pxcor = 9 and pycor = 7] [set plabel ["El Farol Bar"]]
  ask patches with [pxcor = 21 and pycor = -21] [set plabel ["Elsewhere"]]

  ;; create the flibs and give them a random chromosome
  ask n-of num-flibs patches [sprout-flibs 1 [
    set shape "flib"
    set color white
    set size 2
    set chromosome ""
    ]
  ]
  set locus 0
  ask flibs [chromosome-genesis]
  reset-ticks
end 

;; Chromosomes are strings randomly built through an iterative procedure. The content of even string positions
;; are 1 or 0: they are the flib's outgoing signals representing respectively the intention to go or not to go
;; to the bar. Odd string positions are occupied by the numerical code of one state.

to chromosome-genesis
  set chromosome word chromosome (word (random 2) (random num-states))
  set locus locus + 1
  if locus < num-states * 2 [chromosome-genesis]
  set locus 0
end 


;;  ----------   RUNTIME PROCEDURES   --------------------------------------------------------------------------------
;;  ------------------------------------------------------------------------------------------------------------------

to go
  set tot_attend 0
  ask flibs [set fitness 0 set state 0]

  repeat 100 [el-farol] ;; a 100 cycles tournament could be seen as a season to "El Farol" bar (i.e. 100 evenings)

  if sum [fitness] of flibs = 0 [  ;; no fitness no progress
    show "fitness null for every flibs"
    stop
  ]
  analyse   ;; some relevant "El Farol" seasonal results are picked and processed
  ask flibs [move] ;; the world displays a snapshot of the bar after the last evening of the season

  conjugation  ;; after every season, one breeding and one mutational event occurs
  ask one-of flibs [mutate]

  tick
end 


;; Operator 1: A SEASON TO EL FAROL BAR
;; -------------------------------------------------------------------------------------------------------------------

to el-farol
  let attendance 0    ;; the variable records the fraction of agents attending the bar during one evening
  flibs-behaviour
  ;; bar attendance is the sum of every flibs' choices
  set attendance sum [choice] of flibs / num-flibs
  ;; comparing the attendance and the threshold value, the (over)crowded state of the bar is determined
  if attendance >= threshold [set crowded 1    ;; if the bar is crowded, reward the flibs that are elsewhere
    ask flibs with [choice = 0] [set fitness fitness + 1] ]
  if attendance < threshold [set crowded 0  ;; if the bar is not crowded, reward the flibs that are attending
    ask flibs with [choice = 1] [set fitness fitness + 1] ]
  set tot_attend tot_attend + attendance ;; the results of every evening of a season is added up
end 

to flibs-behaviour
  ask flibs [
    ;; the flibs state is updated
    set state read-from-string item (4 * state + 2 * crowded + 1) chromosome
    ;; each flib processes its choice (to go or not to go)
    set choice read-from-string item (4 * state + 2 * crowded) chromosome
  ]
end 

to analyse
  set best max [fitness] of flibs
  set worst min [fitness] of flibs
  ask flibs [set color scale-color red fitness 100 0]
  set sigma_attend sigma_attend + tot_attend / 100
  update-lorenz-and-gini
  diversity-assessment
  set sigma_divers sigma_divers + diversity
end 

to update-lorenz-and-gini  ;; borrowed from Wilensky's model "Wealth Distribution"
  let sorted-comfort sort [fitness] of flibs
  let total-comfort sum sorted-comfort
  let comfort-sum-so-far 0
  let index 0
  set gini-index-reserve 0
  set lorenz-points []
  repeat num-flibs [
    set comfort-sum-so-far (comfort-sum-so-far + item index sorted-comfort)
    set lorenz-points lput ((comfort-sum-so-far / total-comfort) * 100) lorenz-points
    set index (index + 1)
    set gini-index-reserve
      gini-index-reserve +
      (index / num-flibs) -
      (comfort-sum-so-far / total-comfort)
    ]
  set sigma-gini sigma-gini + ((gini-index-reserve / num-flibs) * 2)
end 

to diversity-assessment
  ;; the value of genomic diversity inside the flibs population is evaluated as the number of different chromosomes
  let sort-chrom sort [chromosome] of flibs
  let index 1
  set diversity 1
  repeat num-flibs - 1 [
    if item index sort-chrom != item (index - 1) sort-chrom [set diversity diversity + 1]
    set index (index + 1)
  ]
  let ApC (2 * num-states) ^ (2 * num-states) ;; number of "All possible Chromosomes"
  ;; the percentage of chromosome diversity is computed differently
  ;; when the number of flibs is less of ApC and when it is more or equal to ApC
  ifelse num-flibs < ApC [set diversity diversity * 100 / num-flibs]
  [set diversity diversity * 100 / ApC]
end 

to move
  ifelse choice = 0
      [move-to one-of patches with [pcolor = blue - 3]]
    [move-to one-of patches with [pcolor = yellow]]
end 


;; Operator 2: REPRODUCTION
;; -------------------------------------------------------------------------------------------------------------------

to conjugation
  ;; the conjugation process requires two flibs' chromosomes: the donor and the recipient:
  ;; just the second one will undergo to hybridization
  ifelse best > worst [select-flibs] [stop]
  ask flib recipient [genetic-shuffling]
end 

to select-flibs
  set donor [who] of one-of flibs with [fitness = best]
  set recipient [who] of one-of flibs
  if donor = recipient [select-flibs]
end 

to genetic-shuffling
  ;; a sequence included between two restriction sites (named a-split and b-split) is randomly chosen
  set a-split random (num-states * 4)
  set b-split random (num-states * 4)
  set locus 0
  hybridization
  set fitness 0
end 

to hybridization
 ;; the chromosome's sequence included between a-split and b-split restriction sites on a random
 ;; flib is replaced by the corresponding sequence on one of the most performing flibs;
 ;; chromosomes are treated as circular
 if a-split < b-split [
    set chromosome replace-item (a-split + locus)
      chromosome (item (a-split + locus) [chromosome] of flib donor)
    set locus (locus + 1) if locus < b-split - a-split
      [hybridization]
  ]
 if a-split > b-split [
    set chromosome replace-item ((a-split + locus) mod (num-states * 4))
      chromosome (item ((a-split + locus) mod (num-states * 4)) [chromosome] of flib donor)
    set locus (locus + 1) if locus < (num-states * 4) - (a-split - b-split)
      [hybridization]
  ]
  set locus 0
end 


;; Operator 3: MUTAGENESIS
;; -------------------------------------------------------------------------------------------------------------------

to mutate
  ;; mutations occur randomly at a given frequency on one locus only
  let dice random length chromosome
  let muton read-from-string item dice chromosome
  ifelse dice mod 2 = 0
    [set chromosome replace-item dice chromosome word ((muton + 1) mod 2) ""]
  [set chromosome replace-item dice chromosome word ((muton + 1) mod num-states) ""]
  set fitness 0
end 




; Copyright 2023 Cosimo Leuci.
; See Info tab for full copyright and license.