Exporting Data for External Analysis (15 min) - Agent-Based Modeling & Social Theory

Sometimes you need more sophisticated analysis than NetLogo provides. Exporting data lets you use Excel, R, Python, or other tools.

File Output Commands¶

Write data to CSV files that other programs can read:

; Open file for writing (do this in setup)
file-open "model-output.csv"
file-print "tick,cooperators,defectors,mean-payoff"
file-close

; Write data each tick (do this in go procedure)
file-open "model-output.csv"
file-print (word ticks "," 
                 count turtles with [strategy = "cooperate"] ","
                 count turtles with [strategy = "defect"] ","
                 mean [payoff] of turtles)
file-close

Better approach using procedures:

to setup
  ; ... other setup code ...
  setup-output-file
end

to setup-output-file
  ; Delete old file and create new one with headers
  if file-exists? "results.csv" [ file-delete "results.csv" ]
  file-open "results.csv"
  file-print "tick,cooperation_rate,mean_payoff,clustering"
  file-close
end

to record-data
  file-open "results.csv"
  let coop-rate count turtles with [strategy = "cooperate"] / count turtles
  let avg-payoff mean [payoff] of turtles
  let clustering-measure calculate-clustering  ; Your custom measure
  
  file-print (word ticks "," coop-rate "," avg-payoff "," clustering-measure)
  file-close
end

to go
  ; ... model update code ...
  record-data  ; Call this every tick or every N ticks
  tick
end

Network Analysis Output¶

Export network structure for analysis in specialized tools:

to export-network
  ; Export edge list
  file-open "network-edges.csv"
  file-print "source,target,weight"
  ask links [
    file-print (word [who] of end1 "," [who] of end2 "," link-weight)
  ]
  file-close
  
  ; Export node attributes
  file-open "network-nodes.csv"
  file-print "id,strategy,payoff,degree"
  ask turtles [
    file-print (word who "," strategy "," payoff "," count link-neighbors)
  ]
  file-close
end

Spatial Data Output¶

Export spatial patterns for GIS or mapping analysis:

to export-spatial-data
  file-open "spatial-data.csv"
  file-print "x,y,population,wealth,satisfaction"
  ask patches [
    if count turtles-here > 0 [
      file-print (word pxcor "," pycor "," 
                       count turtles-here ","
                       mean [wealth] of turtles-here ","
                       mean [satisfaction] of turtles-here)
    ]
  ]
  file-close
end

Activity: Data Export Practice¶

Choose one type of data export and implement it:

Time series: Track 3-4 key variables over time
Network data: Export agent connections and attributes
Spatial data: Export location-based information
Test your export by running model and checking output file

Reproducible Research¶

Document your analysis process:

Save parameter settings used for each analysis
Record random seeds so others can reproduce exact results
Document data processing steps from model output to final conclusions
Share both model files and analysis scripts

Course Modules

Using NetLogo’s Built-in Analysis Tools (20 min)

Course Modules

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