Emergence example: pedestrian flows

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Parent of 1 model: EmergenceWithPerturbation preview imageEmergenceWithPerturbation
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Emergence example: pedestrian flows

AUTHOR

Giangiacomo Bravo

WHAT IS IT?

This model shows the emergence of coherent behaviour starting from simple rules.

HOW IT WORKS

Agents are either red or blue. Red ones move left following straight tracks (grey bands in the simulated space). Blue ones move right. If an agent detects another agent in front of it, it changes its track. Agents reaching the space edge are removed from the simulation and replaced by new ones.

HOW TO USE IT

The setup button sets up the model. The parameter n-agents controls the number of agents in the simulation. The go button starts the simulation.

THINGS TO NOTICE

After e certain number of ticks, agents no longer change their tracks. A coherent pattern of behaviour has emerged, where in each track either all agents move left or all agents move right. This on the basis of simple micro-level rules and without the need of macro-level coordination.

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globals [changes]

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to setup
  ca
  ask patches [
    ifelse pycor mod 2 = 0 [set pcolor 8] [set pcolor 9]
  ]
  ask n-of n-agents patches [
    sprout 1 [
      set shape "person"
      set size 1.2
      ifelse random 2 = 0 [set heading 90 set color blue] [set heading 270 set color red]
    ]
  ]
  reset-ticks
end 

to go
  set changes 0
  move
  tick
  if ticks > 5000 [stop]
end 

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

to move
  ask turtles [
    ifelse any? other turtles-on patch-ahead 1
      [
        ifelse random 2 = 0
          [if ycor < max-pycor [if not any? turtles-on patch xcor (ycor + 1) [set ycor ycor + 1 set changes changes + 1]]]
          [if ycor > min-pycor [if not any? turtles-on patch xcor (ycor - 1) [set ycor ycor - 1 set changes changes + 1]]]
      ]
      [
        fd 1
      ]
  ]
end

There are 3 versions of this model.

Uploaded by When Description Download
Giangiacomo Bravo about 3 years ago Reverted to older version Download this version
Giangiacomo Bravo about 3 years ago Introduction of a wall perturbating the flow Download this version
Giangiacomo Bravo about 9 years ago Initial upload Download this version

Attached files

File Type Description Last updated
Emergence example: pedestrian flows.png preview Preview for 'Emergence example: pedestrian flows' about 9 years ago, by Giangiacomo Bravo Download

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