Axelrod_Cultural_Dissemination
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;; Axelrod's Model for Cultural Evolution is an agent-based model described by ;; Robert Axelrod in his paper: ;; Axelrod, R. 1997. “The dissemination of culture - A model with local convergence and global polarization.” ;; Journal of Conflict Resolution 41:203-226. ;; ;; 'Axelrod_Cultural_Dissemination.nlogo' implements this model with one extension: agents can move. ;; ;; 2013 Arezky H. Rodríguez (arezky@gmail.com) ;; ;; -------------------------------------------------- ;; ;;;;;;;;;;;;;;;;; ;;; VARIABLES ;;; ;;;;;;;;;;;;;;;;; globals [ number_of_agents ;; number of all agents in the society Cult_max ;; number related with the maximun cultural value of an agent (q-1 q-1 q-1 ... q-1) number_of_cultures ;; number of cultures in the society number_of_possible_interactions ;; number of possible interactions at each tick that could be according to cultural overlap between agents number_of_real_interactions ;; number of real interactions at each tick that occurs according to cultural overlap between agents time ;; time component-size ;; number of turtles explored so far in the current component giant-component-size ;; number of turtles in the giant component number_of_cultural_regions ;; number of cultural regions simply connected number_of_active_agents ;; number of agents which have at leat one neighbor (other agent in-radius 'radius' with ;; overlap between 0 and 1 (not including the extremes of the intervale) ] turtles-own [ culture ;; culture of an agent explored? ;; if the agent is already explored (or not) when determining number of cultural regions ] patches-own [ ] ;; -------------------------------------------------- ;; ;;;;;;;;;;;;;;;;;;;;;;;; ;;; SETUP PROCEDURES ;;; ;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; General setup settings ;; to setup clear-all clear-all-plots resize-world 0 (world-size - 1) 0 (world-size - 1) ;; defining the size of the society (number of patches set number_of_agents (world-size * world-size) ;; one agent per patch set-patch-size 360 / world-size ;; setting patch size for good looking ask patches [set pcolor 34] ;; setting color of patches set giant-component-size 0 ;; initializing the number of agent in the bigger cultural domain set number_of_cultural_regions 0 ;; initializing the number of the cultural domains setup-turtles ;; creating the agents, locating them and setting their cultural values randomly reset-ticks set time 0 end ;; ;; Turtles settings ;; to setup-turtles set-default-shape turtles "default" create-turtles number_of_agents [ set size 0.8 while [any? other turtles-here] [ move-to one-of patches ] ;; setting agent location. Only one agent at each patch ] setup-culture-max ;; asigning a value to the culture with maximum traits value setup-agent-culture ;; setting agents culture count-cultures ;; counting the amount of different cultures at time = 0 do-plots ;; plotting for visualization end ;; ;; setting agents culture ;; to setup-agent-culture ask turtles [ set culture [] repeat f [ set culture lput random q culture ;; setting a random trait to each feature of the agent culture ] setup-agent-culture-color ;; setting a color for an agent according to its culture ] end ;; ;; asigning a value to the culture with maximum traits values ;; it is done mapping the traits value to a number in base q ;; to setup-culture-max let i 1 let suma 0 repeat F [ set suma suma + q ^ (F - i) set i i + 1 ] set Cult_max ((q - 1) * suma) end ;; -------------------------------------------------- ;; ;;;;;;;;;;;;;;;;;;;;;; ;;; MAIN PROCEDURE ;;; ;;;;;;;;;;;;;;;;;;;;;; to go clear-links let repeating? true while [repeating?] [ set number_of_possible_interactions 0 ;; setting initial values set number_of_real_interactions 0 set number_of_active_agents 0 ask turtles [ ;; asking agents to move and interact localy if random-float 1.0 < veloc [ random-move ] ;; moving (in case veloc > 0) cultural-interaction ;; all agents interact in asyncronous-random updating ] if number_of_active_agents = 0 [set repeating? false] ;; stopping when there are no active agents set time time + 1 ;; it happens when each agent has full or null overlap with ;; each of its neighbors. ;; neighbors are all agents in radius 'radius' count-cultures ;; counting the amount of different cultures do-plots ;; and plotting for visualization tick ] count-turtles-on-bigger-region ;; when running stops, count number of agents in the bigger domain ;; and the amount of domains if saving? [ ;; to save if saving? true let file_out_name (word "F" F "L" world-size "r" radius ".dat") ;; it is saved a file with values of file-open file_out_name ;; q, number of agents in the bigger cultural domain (normalized), number of cultural domains (normalized) file-print (word q " " (giant-component-size / number_of_agents) " " (number_of_cultural_regions / number_of_agents)) file-close ] stop end ;; ;; calculating number cultures on the whole society ;; to count-cultures let list_of_cultures [] ask turtles [ ; setting agent culture in base q let i 1 let suma 0 repeat F [ set suma suma + item (i - 1) culture * q ^ (F - i) ;10 ^ (F - i) set i i + 1 ] set list_of_cultures fput suma list_of_cultures ;; including each culture (its corresponding number) in a list ] set list_of_cultures remove-duplicates list_of_cultures ;; removing repeted cultures set number_of_cultures length list_of_cultures ;; the amount of different cultures is the length of the list end ;; ;; counting the number of agent in the biggest culture ;; to count-turtles-on-bigger-region ; first it is linked all agents of the same culture (each agent looks for a neighbour which is in its neighborhood (agent inside in radius) ask turtles [ creates-links-with-same-cultural-neighbours-in-neighborhood-of-radio-radius ] find-all-components ;; exploring each connected network finding and counting agents of the same culture end ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;; Network Exploration ;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; to find all the connected components in the network, their sizes and starting turtles ;; to find-all-components ask turtles [ set explored? false] ;; keep exploring till all turtles get explored loop [ ;; pick a node taht has not yet been explored let starting_turtle one-of turtles with [ not explored? ] if starting_turtle = nobody [ stop ] ;; reset the number of turtles found to 0. This variable is updated each time we explore an unexplored node set component-size 0 ;; find all turtles reachable from this node ask starting_turtle [ explore ;; after each explore procedure finishes it is explored one cultural region, so increment the counter ( number_of_cultural_regions ) set number_of_cultural_regions number_of_cultural_regions + 1 ] ;; the explore procedure updates the component-size variable, so check, have we found a new giant component? if component-size > giant-component-size [ set giant-component-size component-size ] ] end ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;; TURTLES' PROCEDURES ;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; Finds all turtle reachable from this node (it is a recursive procedure) ;; to explore ;; turtle procedure if explored? [ stop ] set explored? true set component-size component-size + 1 ask link-neighbors [ explore ] end ;; ;; agents look for a neighbor to interact ;; to cultural-interaction ;counting any turtle for interacting at distance less than radius and with overlap between 0 and F (not includying) let number_of_possible_neighbors count other turtles in-radius radius with [(0 < overlap_between self myself ) and (overlap_between self myself < F)] ;if there are neighbors for interacting, setting agent neighbor. if number_of_possible_neighbors > 0 [ set number_of_active_agents number_of_active_agents + 1 let neighbor_turtle one-of other turtles in-radius radius ;interacting the cultures let target_turtle self culturally_interacting target_turtle neighbor_turtle ] end ;; ;; an agent creates a link with all it neighbors with the same culture ;; to creates-links-with-same-cultural-neighbours-in-neighborhood-of-radio-radius let neighborhood other turtles in-radius radius ask neighborhood [ if overlap_between self myself = F [ create-link-with myself ] ;; overlap_between is a reporter ] end ;; ;; setting interaction between target agent and neighbor selected ;; to culturally_interacting [target_turtle neighbor_turtle] let overlap overlap_between target_turtle neighbor_turtle if (0 < overlap and overlap < F ) [ set number_of_possible_interactions number_of_possible_interactions + 1 ;; if interaction is possible increment the counter let prob_interaction (overlap / F) ;; setting the probability of interaction if random-float 1.0 < prob_interaction [ set number_of_real_interactions number_of_real_interactions + 1 ;choosing a feature position randomly where the two cultures are different let trait random F ;; generates a number between 0 and (F - 1) let trait_selected? false while [not trait_selected?] [ ifelse (item trait [culture] of target_turtle = item trait [culture] of neighbor_turtle) [ set trait ((trait + 1) mod F) ;; looking for other feature ] [ set trait_selected? true ;; found a feature with different cultural traits ] ] let new_cultural_value (item trait [culture] of neighbor_turtle) set culture replace-item trait culture new_cultural_value ;; replacing/copying the neighbor trait setup-agent-culture-color ;; updating the agent color according to its new culture ] ] end ;; ;; random move according to 'steplength' and 'angle' for rotating ;; to random-move let var (random angle + 1) ;; selecting and angle to rotate set heading (heading + var - ((angle + 1) / 2)) ;; mapping for left and right ifelse can-move? steplength ;; in case of no periodic boundary conditions, if agent at the border [ ;; rotate with any angle for new direction forward steplength ] [ set heading random 360 forward steplength ] end ;; ;; setting the color according to the culture ;; to setup-agent-culture-color ;setting agent culture in base q let i 1 let suma 0 repeat F [ set suma suma + item (i - 1) culture * q ^ (F - i) set i i + 1 ] let Cult_base_q suma ;setting the corresponding color to the turtle according to the culture_base_q value. a range of blue is selected set color (9.9 * Cult_base_q / Cult_max) + 100 end ;;;;;;;;;;;;;; ;;; GRAPHS ;;; ;;;;;;;;;;;;;; to do-plots ;setting the plot of Cultures set-current-plot "Graph" set-current-plot-pen "Cultures" plotxy time (number_of_cultures / q ^ F) set-current-plot-pen "Possible interactions" plotxy time (number_of_possible_interactions / number_of_agents) set-current-plot-pen "Real interactions" plotxy time (number_of_real_interactions / number_of_agents) set-current-plot-pen "Active agents" plotxy time (number_of_active_agents / number_of_agents) end ;;;;;;;;;;;;;;;;;;;;;;;;; ;;; REPORT PROCEDURES ;;; ;;;;;;;;;;;;;;;;;;;;;;;;; ;; reporting overlap between two agents to-report overlap_between [target_turtle neighbor_turtle] let suma 0 (foreach [culture] of target_turtle [culture] of neighbor_turtle [ if ?1 = ?2 [ set suma suma + 1] ] ) report suma end ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;; PATCHES' PROCEDURES ;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; there are no patches procedures
There is only one version of this model, created over 11 years ago by Arezky Hernández-Rodríguez.
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Axelrod_Cultural_Dissemination.png | preview | Preview for 'Axelrod_Cultural_Dissemination' | over 11 years ago, by Arezky Hernández-Rodríguez | Download |
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