Introduction to Computing for Complex Systems

(Lab Session 1)

Daniel Martin KatzMichigan State University

College of Law

Implementation: From Concept to Product

Implementation

It is important to understand the canonical scholarship as highlighted in the lecture

However, model implementation and the mechanics of other forms of analysis is often the barrier to entry for most scholars

Implementation is the link between concept and scientific product

Different Software Packages

Netlogo = Introductory Modeling Environment (Agent Based Models & System Dynamics)

R = Platform for Statistical Analysis (Includes the IGraph Library for Networks)

Vensim / Nova = Development of System Dynamics and Ecological Models

Pajek = Basic Software for Empirical Analysis & Visualization of Networks

Python = Object Oriented Programming Language Flexible and Fast but High Bar to Entry

Getting Started In

Getting Started In Netlogo

Netlogo is an Introductory Modeling Environment

Developed By Uri Wilensky @ Northwestern in 1999

Maintained by Center for Connected Learning & Computer-Based Modeling @ Northwestern

Getting Started In Netlogo

Syntax is Inherited from the old “Logo” Language

Resnick (1991)

Wilensky (1999)

Papert & Minsky (1967)

Getting Started In Netlogo

Features Aspects of Programming But is Not a General Language ( C++, Python, Java)

Arguably Easier To Learn Than A General Language

Serves the Implementation Needs of Many Modelers

Getting Started In Netlogo

Agent Based Models, System Dynamics Models, Network Models, GIS, Etc.

Download @ ccl.northwestern.edu/

Should Also Acquire User Manual & Dictionary

Version 4.1, Version 4.1 3D, Version 3.1.5

Getting Started In Netlogo

HIV / AIDS VOTING

Where To Get Help

Where To Get Help

Netlogo Front Page

Getting Started in Netlogo

Getting Started in Netlogo

Files Have a Extension of .nlogo

Interface

Information

Procedures

Interface

Information

Procedures

Edit theInformation

Interface

Information

Procedures

Code for the

Schelling’sSegregation

Model

The Models Library

Explore the Available Models

Getting Started in Netlogo

Getting Started in Netlogo

Getting Started in Netlogo

Getting Started in Netlogo

Controls

executes specific commands “on the fly”

Buttons

Command Center

“once” buttons execute one Action

“forever” buttons repeat the same action (Until Stopped)

Settings

Sliders

Switchers

Select a value from a list

Adjust a quantity by increments

Choosers

Set a Boolean variable (true/false)

Monitors

Plots

Offers the Current Value of Variables

Displays the Time Series Plot for a Given Variable or Variables

Views

The Netlogo Language

Four Types of Agents

Patches

Turtles

Links

The Observer

Patches

Tile  System  with  (0,0)  Center  Origin

pxcormin-­‐pxcormax-­‐pxcorworld-­‐heightworld-­‐width

View the Settings

View the Settings

View the Settings

View the Settings

View the Settings

What is a Torus?

Why is It 33 x 33?

View the Settings

Patches: Key Things

Patches do not move -- they are fixed

Patches can breed turtles

Patches can have assigned variables

Patches belong to an agent set

Consulting the Netlogo Dictionary

Descriptions of Patch Primitives Can Be Accessed

Through theNetlogo

Dictionary

Turtles

Turtles  move  on  top  of  the  patches

Have  decimal  coordinates  (xcor,  ycor)  

Have  an  orientation  (heading)  

Can  have  different  shapes  

Turtles

Classic  Hawk  &  Dove  Model  from  Evolutionary  Game  Theory

Runs  in  Netlogo  Version  3.1.5

Inspect Turtles

Right Click on a Turtle (Ctrl + Click on Mac)

Watch a Specific Turtle

Right Click on a Turtle (Ctrl + Click on Mac)

Lots of Different Turtle Shapes

Turtles: Key Things

Turtles move around the environment

Turtles can have various shapes

Turtles can have different variables

Turtles belong to an agent set

Colors

color  =  agentspcolor  =  patches

Select  a  Major  Color  by  Name  

Customize  Colors  Using  ##  from  Chart

Exploring the Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

http://ccl.northwestern.edu/netlogo/models/Fire

http://ccl.northwestern.edu/netlogo/models/Fire

The Forest Fire Model

Tally the Average of five model runs

For Values

50, 55, 60, 65

The Forest Fire Model

Average2.6

The Forest Fire Model

Average2.6

Average5.8

The Forest Fire Model

Average2.6

Average5.8

Average66.5

The Forest Fire Model

Average2.6

Average5.8

Average66.5

Average93.9

Average5.8

Average66.5

Parallel Processing on Percolation Threshold

Lets Do Some additional in Class Data Collection

On Our Fire Model

56

57

58

59

Now LetsDiscuss

The Results

Explore the Code

The Forest Fire Model

;; is for CommentsNot Active

code

What is a Global?

Look it up in the dictionary

What is a Global?

What is a breed?

again, look it up in the dictionary

What is a breed?

The Forest Fire Model

The Forest Fire Model