View source for NetLogo

{{Short description|Programming language}}
{{Infobox programming language
| name = NetLogo
| logo = [[File:NetLogo-Logo.svg|260px]]
| logo caption = 
| screenshot = NetLogo-7.0.0-beta2-Interface.png
| screenshot caption = NetLogo [[graphical user interface]]
| family = [[Lisp (programming language)|Lisp]]
| paradigms = [[Multi-paradigm programming language|multi-paradigm]]: [[List of educational programming languages|educational]], [[Procedural programming|procedural]], [[Computer simulation#Types|agent-based]], [[Simulation language|simulation]]
| designer = [[Uri Wilensky]]
| developer = [[Northwestern University]] [[Center for Connected Learning and Computer-Based Modeling (CCL)]]
| released = {{Start date and age|1999}}
| latest release version = {{wikidata|property|edit|reference|P348}}
| latest release date    = {{start date and age|{{wikidata|qualifier|P348|P577}}}}
| typing = [[Dynamic typing|Dynamic]], [[Strong typing|strong]]
| scope = [[Scope (computer science)#Lexical scoping and dynamic scoping|Lexical]]
| programming language = [[Scala (programming language)|Scala]], [[Java (programming language)|Java]]
| platform = [[IA-32]], [[x86-64]]
| operating system = [[Cross-platform]]: [[Java virtual machine|JVM]]
| license = [[GNU General Public License|GPL]]
| file ext = .nlogox, .nlogo, .nlogo3d, .nls
| website = {{URL|www.netlogo.org}}
| implementations = [[Scala (programming language)|Scala]] (Desktop), [[JavaScript]] (Web)
| dialects = 
| influenced by = [[Logo (programming language)|Logo]], [[StarLogo]]
| influenced = 
}}

'''NetLogo''' is a [[open-source]] [[programming language]] and [[integrated development environment]] (IDE) for [[Agent-based model|agent-based]] modeling. It is part of a family of agent-based modeling products, which includes [[NetLogo Web]], [[NetLogo 3D]], [[NetTango]], [[TurtleUniverse]], [[HubNet]], [[HubNet Web]], and [[BehaviorSpace]]. It is currently being maintained by the [[Center for Connected Learning and Computer-Based Modeling (CCL)]] at the [[School of Education and Social Policy (SESP)]], [[Northwestern University]].

NetLogo, the programming language, is a [[Lisp]]-style programming language with support for [[List (abstract data type)|lists]], “agentsets”, [[String (computer science)|strings]], [[Input/output]], and plotting. Like the software itself, the programming language is also extensible using the built-in extension manager. Many extensions are available, including support for [[Arrays]], [[Hash table|Tables]], [[Matrix (mathematics)|Matrices]] as well as integrations with popular programming languages like [[R (programming language)|R]] and [[Python (programming language)|Python]].

==About==
NetLogo was designed by [[Uri Wilensky]], in the spirit of the programming language [[Logo (programming language)|Logo]], to be "low threshold and no ceiling". It teaches programming concepts using [[Agent-based model|agents]] in the form of ''turtles'', ''patches'', ''links'' and the ''observer''.<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/docs/programming.html#agents |title=Types of Agents in NetLogo |last=Wilensky |first=Uri |date=1999–2019 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref> NetLogo was designed with multiple audiences in mind, in particular: teaching [[child]]ren in the education community, and for [[Subject-matter expert|domain experts]] without a programming background to model related phenomena.<ref>{{cite conference
|last1=Kornhauser |first1=Daniel
|last2=Rand |first2=William
|last3=Wilensky |first3=Uri
|location=Chicago, Illinois
|date=November 15–17, 2007
|conference=Agent2007
|title=Visualization Tools for Agent-Based Modeling in NetLogo
|url=http://ccl.northwestern.edu/papers/2007/Kornhauser-Agent-2007.pdf |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University <!-- publisher: |location=Evanston, Illinois --> |access-date=2019-05-03
}}</ref>
Thousands of scientific articles have been published using NetLogo.<ref name="ref-list">{{cite web |url=http://ccl.northwestern.edu/netlogo/references.shtml |title=NetLogo References |last=Wilensky |first=Uri |date=1999–2025 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2025-01-24}}</ref>

The NetLogo environment enables exploration of [[emergent phenomena]]. It comes with an extensive models library including models in a variety of domains, such as [[economics]], [[biology]], [[physics]], [[chemistry]], [[psychology]], and [[system dynamics]].<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/models/ |title=NetLogo Models Library |last=Wilensky |first=Uri |date=1999–2025 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref> NetLogo allows exploration by modifying switches, sliders, choosers, inputs, and other interface elements.<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/docs/interface.html#interface |title=Interface Guide |last=Wilensky |first=Uri |date=1999–2025 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2020-01-24}}</ref> Beyond exploring, NetLogo allows authoring new models and modifying extant models.

NetLogo is open source and freely available from the NetLogo website.<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/download.shtml |title=Download NetLogo |last=Wilensky |first=Uri |date=1999–2019 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref> It is in use in a wide variety of educational contexts from elementary school to graduate school.<ref>{{cite web |url=http://ccl.northwestern.edu/papers/2011/sengupta2011.pdf|title=Lowering the Learning Threshold: Multi-Agent-Based Models and Learning Electricity |last1=Sengupta |first1=Pratim |last2=Wilensky |first2=Uri |date=2011 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref><ref>{{cite book |last1=Wilensky |first1=Uri |last2=Novak |first2=Michael |date=2010 |title=Epistemology and Science Education: Understanding the Evolution vs. Intelligent Design Controversy |chapter=Teaching and Learning Evolution as an Emergent Process: The BEAGLE project (chapter 10) |url=http://ccl.northwestern.edu/papers/2010/BEAGLE-chapter-final-distribute.pdf |editor-last=Taylor |editor-first=R. |editor2-last=Ferrari |editor2-first=M. |location=New York |publisher=Routledge }}</ref><ref>{{cite journal |url=http://ccl.northwestern.edu/papers/2009/Blikstein&Wilensky_AnAtomIsKnown.pdf |title=An Atom is Known by the Company it Keeps: A Constructionist Learning Environment for Materials Science Using Agent-Based Modeling (CCL) |last1=Blikstein |first1=Paulo |last2=Wilensky |first2=Uri |journal=International Journal of Computers for Mathematical Learning |year=2009 |volume=14 |issue=2 |pages=81–119 |doi=10.1007/s10758-009-9148-8|s2cid=10500589 }}</ref><ref>{{cite journal |url=http://ccl.northwestern.edu/papers/2009/Levy&Wilensky_ConnectedChemistry.pdf |title=Students' Learning with the Connected Chemistry (CC1) Curriculum: Navigating the Complexities of the Particulate World |journal=Journal of Science Education and Technology |doi=10.1007/s10956-009-9145-7 |last1=Levy |first1=Sharona T. |last2=Wilensky |first2=Uri|year=2009 |volume=18 |issue=3 |pages=243–254 |bibcode=2009JSEdT..18..243L |s2cid=62526922 }}</ref> Many teachers make use of NetLogo in their curricula.<ref>{{Cite web |url=http://ccl.northwestern.edu/courses.shtml |title=University, secondary, and online courses that utilize NetLogo |last=Wilensky |first=Uri |date=1999–2019 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref><ref>{{Cite web |url=http://davidmholmes.net/Stuy |title=Comp Sci at Stuyvesant with D. Holmes |last=Holmes |first=David M. |date=<!--Undated--> |website=Professional web site for David Holmes |location=New York City, New York, United States |access-date=2019-05-03}}</ref> NetLogo is also widely used in scientific research having been used in several thousand research papers.<ref name="ref-list" />

NetLogo was designed and authored by Uri Wilensky,<ref>{{cite web |url=http://www.sesp.northwestern.edu/profile/?p=89&/UriWilensky/ |title=Profile: Dr. Uri Wilensky |access-date=2014-12-21 |archive-date=2014-12-21 |archive-url=https://archive.today/20141221144308/http://www.sesp.northwestern.edu/profile/?p=89&/UriWilensky/ |url-status=dead }}</ref> director of [[Northwestern University]]'s Center for Connected Learning and Computer-Based Modeling (CCL).<ref name="netlogo_creation">{{cite conference
|last1=Tisue |first1=Seth
|last2=Wilensky |first2=Uri
|conference=Agent2004
|location=Chicago, Illinois
|access-date=October 4, 2012
|date=October 2004
|url=http://ccl.northwestern.edu/papers/agent2004.pdf
|title=NetLogo: Design and Implementation of a Multi-Agent Modeling Environment
}}</ref>

== Features ==
NetLogo supports many features<ref>{{cite web |title=What is NetLogo? |url=https://docs.netlogo.org/7.0.0-beta2/whatis.html |website=NetLogo User Manual |publisher=NetLogo |access-date=4 August 2025}}</ref> including but not limited to:
* Cross-platform support: NetLogo supports Windows, Linux, and MacOS with the option to build from source
* Cross-platform reproducibility: NetLogo produces consistent output across platforms
* Double precision [[floating point]] numbers
* First-class function values: anonymous procedures and reporters
* On the fly interactions: NetLogo command center can be used to issue commands on the fly
* Interface Builder: NetLogo packages a drag-and-drop UI interface builder 
* Agent monitors: The Agent Monitor allows for inspecting and controlling agents
* Export and import functions (export data, save and restore state of model, make a movie)
* System Dynamics Modeler: NetLogo includes basic support for dynamic system modeling
* NetLogo 3D: NetLogo 3D offers support for modeling 3D worlds
* Headless mode: NetLogo can run headlessly, allowing batch runs from the command line
* BehaviorSpace: a tool used to collect data from multiple runs of a model with varying parameters
* Extensions: NetLogo supports extensions for both the software and the programming language in the form of [[JAR (file format)|JAR]] files

== Books ==

Several books have been published about NetLogo.<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/resources.shtml |title=NetLogo: Resources and Links |last=Wilensky |first=Uri |date=1999–2019 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref>

Books available in print include:

*{{cite book |title=An introduction to agent-based modeling: Modeling natural, social and engineered complex systems with NetLogo |last1=Wilensky |first1=Uri |last2=Rand |first2=William |publisher=[[MIT Press]] |year=2015 |isbn=978-0-262-73189-8 |location=Cambridge }}
*{{cite book |title=Agent-Based and Individual-Based Modeling: A Practical Introduction |last1=Railsback |first1=Steven F. |last2=Grimm |first2=Volker |publisher=[[Princeton University Press]] |year=2011 |isbn=978-0-691-13674-5 |location=Cambridge }}
*{{cite book |title=Spatial Simulation: Exploring Pattern and Process |last1=O'Sullivan |first1=David |last2=Perry |first2=George |publisher=[[John Wiley & Sons|Wiley-Blackwell]] |year=2013 |isbn=978-1-119-97079-8 }}
*{{cite book |title=Simulation for the Social Scientist, Second Edition |last1=Gilbert |first1=Nigel |last2=Troitzsch |first2=Klaus G. |publisher=[[McGraw Hill]] |year=2005 |isbn=978-0-335-21600-0 |location=London }}
*{{cite book |title=Computational Neuroscience and Cognitive Modeling (CCL) |last=Andersen |first=Britt |publisher=Sage |year=2014 |location=London |isbn=978-1-4462-4930-7}}
*{{cite book |title=Agent Based Modeling for Archaeology: Simulating the Complexity of Societies |last1=Romanowska |first1=Iza |last2=Wren |first2=Colin D. |last3=Crabtree |first3=Stefania A. |publisher=Santa Fe Institute Press |year=2021 |location=Santa Fe, New Mexico |isbn=978-1-947864-25-2}}

Books available online include:

* {{cite web |url=http://jmvidal.cse.sc.edu/papers/mas.pdf |title=Fundamentals of Multiagent Systems Using NetLogo |last=Vidal |first=Jose |date=2010}}
* {{cite web |title=NetLogo User Manual |url=https://docs.netlogo.org/7.0.0-beta2/NetLogo%20User%20Manual.pdf |website=NetLogo User Manual |publisher=Center for Connected Learning and Computer Modeling, Northwestern University |access-date=4 August 2025|date=2025}}

==Online courses==

{{As of|2019}}, several [[massive open online course]]s are being offered that use NetLogo for assignments and/or demonstrations:
* {{cite web |url=http://www.complexityexplorer.org/ |title=Introduction to Complexity |last=Mitchell |first=Melanie |publisher=Santa Fe Institute}}
* {{cite web |url=https://www.coursera.org/course/modelthinking |title=Model Thinking |last=Page |first=Scott E. |publisher=University of Michigan}}
*{{cite web |url=http://bert.stuy.edu/pbrooks/fall2018/materials/intro-year-1/intro-pilot-1_homepage.htm |title=Introduction to Comp Sci |last=Brooks |first=Peter |publisher=[[Stuyvesant High School]]}}

==Technical foundation==
NetLogo is [[free and open-source software]], released under a [[GNU General Public License]] (GPL).<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/docs/faq.html#license|title=Under what license is NetLogo released? Is the source code available?}}</ref> Commercial licenses are also available. It is written in [[Scala (programming language)|Scala]] and  [[Java (programming language)|Java]] and runs on the [[Java virtual machine]] (JVM).<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/faq.html|title=NetLogo Frequently Asked Questions (FAQ) |date=December 14, 2015}}</ref> At its core is a hybrid interpreter/compiler that partially compiles user code to JVM bytecode.<ref name="faster_turtles">{{cite conference
|last1=Stonedahl |first1=Forrest
|last2=Tisue |first2=Seth
|last3=Wilensky |first3=Uri
|conference=Agent 2006
|location=Chicago, Illinois
|access-date=October 22, 2012
|date=2006
|url=http://ccl.northwestern.edu/papers/sond_tis_wil_breeding.pdf
|title=Breeding faster turtles: Progress towards a NetLogo compiler
}}</ref>

NetLogo Web is a version that runs on JavaScript, instead of the JVM, so models may be run in a web browser. However, it does not yet have all features of the desktop version.

==Models==
===Models Library===
NetLogo provides a built-in models library of over 600 models across multiple disciplines, including [[social science]], [[psychology]], [[mathematics]], [[physics]], [[biology]], [[economics]], [[game theory]], and more. Many of those models are part of the ''An introduction to agent-based modeling: Modeling natural, social and engineered complex systems with NetLogo'' textbook.<ref>{{cite book |title=An introduction to agent-based modeling: Modeling natural, social and engineered complex systems with NetLogo |last1=Wilensky |first1=Uri |last2=Rand |first2=William |publisher=[[MIT Press]] |year=2015 |isbn=978-0-262-73189-8 |location=Cambridge }}</ref>

====Wolf-Sheep Predation====
The '''Wolf-Sheep Predation''' model is simple multiagent model in NetLogo,<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation|title=Wolf Sheep Predation}}</ref> which is shown in the screenshot above. It models the population growth of a predator/prey system over time. It has the following characteristics:

* There are two breeds of turtles, called ''sheep'' and ''wolves''.
* Sheep and wolves move randomly and have limited energy.
* Wolves and sheep lose energy by moving. If a wolf or sheep has zero energy, it dies.
* Sheep gain energy by eating grass.
* Wolves gain energy by eating sheep.
* Both wolves and sheep can reproduce, sharing energy with their offspring.

====Traffic Grid====
The '''Traffic Grid''' model<ref>{{cite web |title=Traffic Grid (GitHub) |url=https://github.com/NetLogo/models/blob/dd42f0586942c93c1a2cba866f7d6e5184e97f0e/Sample%20Models/Social%20Science/Traffic%20Grid.nlogox#L4 |website=GitHub |publisher=Center for Connected Learning and Computer Modeling, Northwestern University |access-date=4 August 2025}}</ref> in NetLogo simulates vehicular movement and traffic light control on a two‑dimensional city grid. Cars accelerate, decelerate, or stop depending on traffic lights, other vehicles, and a user‑defined speed limit. The model is designed to demonstrate urban traffic dynamics and gridlock formation while allowing users to experiment with traffic management strategies.

'''Features:'''
* Cars accelerate until reaching the speed limit, slow down behind other cars, and stop for red lights.
* Traffic lights can be controlled either:
** '''Manually''' – users select intersections and toggle lights directly.
** '''Automatically''' – lights switch phases each cycle based on a user‑defined schedule.
* Global variables include:
** '''Grid size''' (number of horizontal and vertical streets)
** '''Number of cars''' in the simulation
** '''Speed limit''' and '''ticks per cycle''' for light changes
* Cars wrap around the world edges, enabling continuous traffic flow.

'''Plots and Outputs:'''
* '''Stopped Cars''' – number of cars stopped each tick
* '''Average Speed of Cars''' – tracks overall traffic flow efficiency
* '''Average Wait Time''' – measures delay per vehicle

The model allows users to test scenarios such as removing lights entirely (causing frequent gridlock), optimizing light phases for maximum flow, and adjusting car density to explore congestion thresholds.

===Modeling Commons===
The '''Modeling Commons'''<ref>{{cite web |title=Quick Introduction to the Modeling Commons |url=https://blog.modelingcommons.org/help/intro |website=Modeling Commons |publisher=Center for Connected Learning and Computer Modeling |access-date=4 August 2025}}</ref> is a web-based platform for sharing and collaborating on NetLogo models, hosted at [http://modelingcommons.org/ modelingcommons.org]. Serving as the official NetLogo modeling forum, it allows users to upload, version, and manage NetLogo models, as well as discuss them and attach related files such as data or documentation. Users can search for models by name, author, tags, or content in the Info and Code tabs, and can create "child" variants of existing models to explore modifications while preserving lineage through a parent–child structure. The platform also supports group-based permissions to manage collaboration and access, and automatically grants coauthor status to anyone who uploads a new version of a model. The site is designed to work with all modern web browsers and is most extensively tested on Chrome, Firefox, and Safari.

==HubNet==

HubNet is a technology that uses NetLogo to run participatory simulations in the classroom.<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/hubnet.html|title=HubNet Guide |date=December 14, 2015}}</ref> In a participatory simulation, a whole group of users takes part in enacting the behavior of a system. Using an individual device, such as a networked computer or [[Texas Instruments]] [[graphing calculator]], each user acts as a separate, independent agent.
One example of a HubNet activity is ''Tragedy of the Commons'',<ref>{{cite web |url=http://ccl.northwestern.edu/netlogo/models/HubNetTragedyoftheCommonsHubNet |title=Tragedy of the Commons HubNet |last=Wilensky |first=Uri |date=2002 |website=The Center for Connected Learning and Computer-Based Modeling (CCL) |publisher=Northwestern University |location=Evanston, Illinois |access-date=2019-05-03}}</ref> which models the economic problem called the [[tragedy of the commons]].

==See also==
*[[Comparison of agent-based modeling software]]

== References ==
{{Reflist}}

==External links==
* {{Official website|ccl.northwestern.edu}}, CCL
** {{Official website|ccl.northwestern.edu/netlogo}}, NetLogo
** [http://ccl.northwestern.edu/netlogo/models/ NetLogo Models Library]
** [http://ccl.northwestern.edu/netlogo/resources.shtml Other NetLogo-related resources on the web]
* [https://twitter.com/netlogo NetLogo news] via [[Twitter]]
* [https://groups.google.com/d/forum/netlogo-users Discussion group for users] hosted by [[Google]]
* [http://groups.google.com/group/netlogo-devel Discussion group for developers] hosted by [[Google]]
* [http://jmvidal.cse.sc.edu/netlogomas NetLogo models of multiagent systems]
*[http://davidmholmes.net/Stuy/1intro/hw.html David M. Holmes' website, containing beginner material for new NetLogo users]{{Dead link|date=March 2023 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Logo programming}}
{{Lisp programming language}}
{{Northwestern}}
{{Authority control}}

{{DEFAULTSORT:Netlogo}}
[[Category:Logo programming language family]]
[[Category:Agent-based programming languages]]
[[Category:Agent-based software]]
[[Category:Pedagogic integrated development environments]]
[[Category:Java platform]]
[[Category:Free software programmed in Scala]]
[[Category:Simulation programming languages]]
[[Category:Simulation software]]