consensus

globals
[
  initial-average
  current-average
  cummulated-difference
  maximum-degree
  ;;; code to isolate view from code (View-controller Model)
  number-of-agents
  initial-degree
  iterations
]

turtles-own
[
  x         ;; current agent value
  newx      ;;next iteration value
  eps       ;; epsilon value: step to approach to the mean value
]

to setup
  configure-model
  create-network
  reset
end 

to configure-model
  set number-of-agents num-agents
  set initial-degree degree
  set iterations iter
end 

to create-network
  ca
  set-default-shape turtles "circle"

  create-turtles num-agents
  ;;create a random network
  ask turtles  [create-links-with n-of degree other turtles]
  set maximum-degree max [count my-links] of turtles
end 

to reset
  clear-all-plots
  reset-ticks

  set current-average 0
  set cummulated-difference 0

  ;; reset agents
  ask turtles [reset-agent]
  set initial-average mean [x] of turtles
  ;; Layout turtles:
  layout-circle (sort turtles) max-pxcor - 2
  display
end 

to reset-agent
  ;; inits agent value at random
  set x random-float 1

  set eps 1 / (maximum-degree + 1)

  set-current-plot "Consensus process"
  create-temporary-plot-pen (word who)
  set-turtle-color
end 

to set-turtle-color
  ifelse (change-color?)
  [set color scale-color blue x 0 1]
  [ifelse ( num-agents < 15 )
      [set color one-of base-colors]
      [set color random 140]
  ]
end 

to reach-consensus
  ;; stops when the number of iteratios is reached
  if (ticks = iter)
  [stop]

  ;; updates the values
  ask turtles [
    set newx x - eps * (x * (count my-links) - sum [x] of link-neighbors)
  ]
  ask turtles [
    set x newx
    if (change-color?)
    [set color scale-color blue x 0 1]
  ]

  ;; calculates the current average (just to check sum/aerage conservation
  set current-average mean [x] of turtles
  ;; calulates the cummulative difference with the average value
  set cummulated-difference sum [(x -  current-average) ^ 2] of turtles / 2
  tick
end