Print Marketplace

;; "Print Marketplace: an Agent-Based Model" 
;; by Michael Gavin, University of South Carolina, 2014.


globals [ 
  year                           ;; statistics are calculated annually (every 100 ticks) 
  books-sold                     ;; calculates cumulative book total
  smoothed-books-of-readers      ;; creates smoothed line of book-sold for easier reading
  smoothed-num-of-printers       ;; creates smooth line of the count of printers for easier reading
  monopoly-radius                ;; distance that printers look for rivals
  monopolize-trade               ;; true/false variable that selects and kills excess printers
  last-years-sales               ;; global calculation of books taken from printers
  ]


;; The following breed types are based very closely on Jeremy Throne's original model. 

turtles-own [ surveillance-radius ]  ;; distance of vision for all turtles

breed [ authors author ]         ;; creates a type of turtle named "author"
authors-own [ manuscripts        ;; provides all "authors" with the ability to store manuscripts
              encouragement ]    ;; provides all "authors" with the ability to receive encouragement

breed [ publishers publisher ]   ;; creates a type of turtle named "publisher"
publishers-own [ submissions ]   ;; provides all "publishers" with the ability to store submissions

breed [ printers printer ]       ;; creates a type of turtle named "printer"
printers-own [ jobs  ]            ;; provides all "printers" with the ability to store jobs

breed [ shippers shipper ]       ;; creates a type of turtle named "shipper"
shippers-own [ cargo ]           ;; provides all "shippers" with the ability to store cargo

breed [ sellers seller ]         ;; creates a type of turtle named "seller"
sellers-own [ inventory ]        ;; provides all "sellers" with the ability to store inventory

breed [ readers reader ]         ;; creates a type of turtle named "reader"
readers-own [ books ]            ;; provides all "readers" with the ability to store books

breed [ censors censor ]         ;; creates a type of turtle (not included in Throne) named "censor"

to setup
  clear-all
  set year 1
  set smoothed-books-of-readers 0
  set monopoly-radius max-monopoly-radius
  reset-ticks
  create-authors 2 [   ;; creates authors and sets their initial properties
    setxy random-xcor random-ycor
    set shape "person"
    set color red                      ;; red signifies where the books are
    set manuscripts 1                  ;; start the author with a single manuscript
  ]
  
  create-publishers 2 [   ;; creates authors and sets their initial properties
    setxy random-xcor random-ycor
    set shape "house"
    set color white                          ;; white signifies there are no books
  ]

  create-printers 2 [     ;; creates printers and sets their initial properties
    setxy random-xcor random-ycor
    set shape "x"
    set color white                        ;; white signifies there are no books
  ]

  create-shippers 2 [    ;; creates shippers and sets their initial properties
    setxy random-xcor random-ycor
    set shape "wheel"
    set color white                       ;; white signifies there are no books
  ]

  create-censors 10 [    ;; creates shippers and sets their initial properties
    setxy random-xcor random-ycor
    set surveillance-radius random 10
    set shape "wolf"
    set color white                       ;; white signifies there are no books
  ]

  create-sellers 2 [         ;; creates sellers and sets their initial properties
    setxy random-xcor random-ycor
    set shape "triangle"
    set color white                          ;; white signifies there are no books
  ]
  
  create-readers 10 [     ;; creates readers and sets their initial properties
    setxy random-xcor random-ycor
    set shape "person"
    set color white                      ;; white signifies where the books are
  ]
end 

;; At go, the turtles are activated. Every 100 ticks a system-level review is performed. STOP after 225 years (22,500 ticks)

to go
  ask authors
  [ move
    solicit-publisher ]
    
  ask publishers
  [ move
    hire-printer
    resist-oppression
     ]
  
  ask shippers
  [ move
    load-cargo
    deliver-cargo ]

  ask censors
  [ move ]

  ask readers
  [ move
    buy-book
    meet-author ]
   
  if ticks = 100 [ perform-review ]
     
  if year = 225 [stop]
 
  tick
end 
  
;; Every 100 ticks (a metric "year"), this procedure is called.   

to perform-review
  
  ;; the following commands control the plot
    set year year + 1 
    set-current-plot "Books Published Annually"
    set-current-plot-pen "Books"
    set smoothed-books-of-readers 0.7 * smoothed-books-of-readers + ( 0.3 * sum [books] of readers ) ; line smooth rule borrowed from Uri Wilensky, "code examples"
    plot smoothed-books-of-readers
    set-current-plot-pen "Population"
    plot (count readers + count authors) / 5
    set-current-plot-pen "Printers"
    set smoothed-num-of-printers 0.6 * smoothed-books-of-readers + ( 0.4 * count printers )
    plot smoothed-num-of-printers
    
   
    set books-sold books-sold + (sum [books] of readers)  ;; total books sold is tabulated
    
    ask one-of censors [ update-radius warn-stationers ]  ;; censors review the state of the system and adjust
    
    ask one-of printers [ restrict-printing ]             ;; printers enforce their monopoly
        
    ask readers [set books 0]                             ;; books levels are reset
    
    expand                                                ;; population growth
    
    reset-ticks 
end 
    
;; censors' procedure, called annually by "perform-review," in which they update their surveillance

to update-radius
  let readers-policed readers in-radius surveillance-radius
  ifelse count readers-policed > 0 [
  let readers-policed-percentage count readers-policed with [books > 0] / count readers-policed
  ifelse readers-policed-percentage > suppression-threshold
  [ set surveillance-radius surveillance-radius + 1 ]  
  [ set surveillance-radius surveillance-radius - 1 ]
  ]
  [ set surveillance-radius surveillance-radius + 1 ]
  
  if surveillance-radius < 0 [ set surveillance-radius 0 ]
end 

;; censors' procedure, called annually by "perform-review," in which they alert stationers

to warn-stationers
  if any? sellers in-radius surveillance-radius
  [ ask sellers in-radius surveillance-radius [ set surveillance-radius [surveillance-radius] of myself ] ]
  
  if any? shippers in-radius surveillance-radius
  [ ask shippers in-radius surveillance-radius [ set surveillance-radius [surveillance-radius] of myself ] ]

  if any? printers in-radius surveillance-radius
  [ ask printers in-radius surveillance-radius 
    [ set surveillance-radius [surveillance-radius] of myself ] ]
    
  if any? publishers in-radius surveillance-radius
  [ ask publishers in-radius surveillance-radius [ 
      set surveillance-radius [surveillance-radius] of myself 
      set submissions 0 ] ]                                     ;; one publisher's manuscripts are confiscated
end 
  
  
;; Expansion is controlled on a simple line. Most turtles have a 50-50 chance of adding a single
;; turtle; readers are adding on an exponential line.

to expand      
     ask one-of authors [ hatch one-of [ 1 0 ] [
         setxy random-xcor random-ycor
         set shape "person"
         set color red
         set manuscripts 1 ] 
     ]
     ask one-of sellers [ hatch one-of [1 0] [ 
          setxy random-xcor random-ycor
          set shape "triangle"
          set color white ]
     ]
     ask one-of publishers [ hatch one-of [0 1] [
          setxy random-xcor random-ycor 
          set shape "house"
          set color white ]
     ]
     ask one-of shippers [ hatch one-of [1 0] [
          setxy random-xcor random-ycor
          set shape "wheel"
          set color white ]
      ]
      ask one-of printers [ hatch one-of [1 0] [
          setxy random-xcor random-ycor
          set shape "x"
          set color white ] 
      ] 
 
;; Reading population set to grow more quickly on a simple but ever-increasing rate.          
      ask one-of readers [ hatch round (year / 50 ) [     ;; creates readers and sets their initial properties
          setxy random-xcor random-ycor
          set shape "person"
          set color white ]  
      ]
  
  ;; but sometimes there's a catastrophe
    check-for-catastrophe 
end 

to check-for-catastrophe
  let catastrophe-throw random 100
  if catastrophe-throw > 95 and catastrophe-throw <= 98 [
    let num-readers-to-die round ( count readers / 5 )
    repeat num-readers-to-die [ ask one-of readers [ die ] ]
      ]
  if catastrophe-throw >= 99 [
    let big-num-readers-to-die round ( count readers / 4 )
    repeat big-num-readers-to-die [ ask one-of readers [ die ] ]
      ]
  if catastrophe-throw <= 1 [
  let big-num-readers-to-hatch round ( count readers / 4 ) 
      ask one-of readers [ hatch big-num-readers-to-hatch [ 
          setxy random-xcor random-ycor
          set shape "person"
          set color white
          ] ]
      ]  
end 


;; Set printer restrictions rule. 

to restrict-printing 
  ifelse mean [ jobs ] of printers < supply-trigger 
  [ set monopoly-radius monopoly-radius + .5 ]
  [ set monopoly-radius monopoly-radius - .5 ]
    
  if monopoly-radius > max-monopoly-radius [ set monopoly-radius max-monopoly-radius ]
  if monopoly-radius < min-monopoly-radius [ set monopoly-radius min-monopoly-radius ]

  repeat one-of [ 5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 ] [ ask one-of printers [ 
    set jobs 0 
    enforce-monopoly ] ]
end  

;; This command moves the turtles. 

to move
  ifelse count censors in-radius surveillance-radius = 0 [
    rt random 50     ;; turns a turtle some portion of 50 degrees to the right
    lt random 50     ;; turns a turtle some portion of 50 degrees to the left
    fd .1            ;; advances forward 1 patch
    ]
   [ 
    rt random 50
    lt random 50
    fd 1
    ]           
end 

;; AUTHOR FUNCTIONS

;; The following procedure is borrowed closely from Throne's original. If authors bump into
;; publishers while carrying a manuscript, the manuscripts are converted to "submissions."

to solicit-publisher
  if any? publishers-here
  [ if manuscripts > 0                        ;; and the author has a book
    [ set manuscripts manuscripts - 1                       ;; remove manuscript from author
      set color white
      ask one-of publishers-here
      [ set submissions submissions + 1       ;; increase submissions to publisher
        set color red ]
    ]
  ]
end 

;; PUBLISHER FUNCTIONS

;; 

to hire-printer
  if submissions > 0 and any? printers-here and count censors in-radius surveillance-radius = 0 [
    set submissions submissions - 1           ;; take a submission from the publisher
    ask one-of printers-here [ set jobs jobs + 1 ]
  ]
end 

;; when their backlog becomes too high, publishers lash out against the censors, but receive punishment in turn.

to resist-oppression
  if submissions > backlog-threshold [                   ; if inventory of submissions has accumulated
    if any? censors in-radius surveillance-radius [      ; publishers look for censors in radius
      ask censors in-radius surveillance-radius [ 
        set surveillance-radius 0                        ; they then basically shut the censor down
        set color red ] ]                                ; and change its color to red. However, they receive backlash (their submissions are lost)
      repeat round ( count publishers / ( random count publishers + 1 ) ) [ ask one-of publishers [ set submissions 0] ]  ;; and any number of publishers feel the pain.
      ask one-of printers [ hatch 1 [                    ; but the moment of social breakdown opens a space for an entrepreneurial printer to open shop
          setxy random-xcor random-ycor
          set shape "x"
          set color white ] 
      ]  
    ]
end 
  

;; SHIPPER PROCEDURES

;; When out of state control shippers face a printer before reorienting. Otherwise, they move normally.

to ship
  ifelse count censors in-radius surveillance-radius = 0 and cargo = 0 and any? printers with [ jobs > 0 ]
  [ face one-of printers with [ jobs > 0 ] 
    rt random 50
    lt random 50
    fd 1 ]  
  [ rt random 50
    lt random 50
    fd .2 ]
end 
  

;; The "load-cargo" procedure is based closely on Throne's original model.
;; If printers bump into a printer, and if the printer has a job, the shipper takes it.

to load-cargo
  if any? printers-here with [ jobs > 0 ] and count censors in-radius surveillance-radius = 0                    ;; if the shipper meets a printer with jobs waiting
  [ ask one-of printers-here with [ jobs > 0 ]               
    [ set jobs jobs - 1
    ]
    ask one-of shippers-here
    [ set cargo cargo + 1 ]                ;; increase cargo of shipper by one unit
  ]
end 

;; The "deliver-cargo" procedure is based closely on Throne's original model.
;; If printers bump into a printer, and if the printer has a job, the shipper takes it.

to deliver-cargo
  if any? sellers-here and count censors in-radius surveillance-radius = 0
  [ let delivery cargo                          ;; turn the cargo into a delivery
    set cargo 0                               
    ask one-of sellers-here
      [ set inventory inventory + delivery ]    ;; increase the inventory of a seller by the amount of the delivary
    ]
end 


;; READER PROCEDURES

;; The "buy book" procedure is based closely on Throne's original.
;; When readers bump into sellers, they buy books. One minor but
;; significant change is that readers can only buy one book per year.

to buy-book
  if any? sellers-here with [ inventory > 0 ] and books < 1            ;; if the reader meets a seller with books to sell and reader has no book.             
  [ ask one-of sellers-here with [ inventory > 0 ]                               
    [ set inventory inventory - 1 ]
    set books books + 1
    set color blue
    ]
end 

;; The "meet-author" procedure is based closely on Throne's original.
;; When readers bump into authors, they encourage authors to write. One minor
;; but significant change is that authors' "writing-threshold" is changed
;; from the original into a slider variable.

to meet-author
 if any? authors-here
  [ ask one-of authors-here
    [ set encouragement encouragement + 1
      if encouragement > writing-threshold                           ;; if authors have enough encouragement
      [ set manuscripts manuscripts + 1                              ;; they write manuscripts
        set encouragement encouragement - writing-threshold ]         ;; and their "encouragement" score is decreased ]
    ]
  ]
end 

;; PRINTER CONTROLS

;; Called above, one printer each year enforces the monopoly by finding
;; and killing one fellow printer within its personal "monopoly-radius." Thus,
;; the smaller the radius the less stringent the monopoly.

to enforce-monopoly
  let printers-to-exclude printers in-radius monopoly-radius with [ who != [who] of myself ] ;; can't enforce against itself!
  if any? printers-to-exclude [
    ask printers-to-exclude [die]         ;; kills off competitors
  ]
end