What is it

In the wolf sheep predation model (Wilensky, 1998), three types of agents interact on a grid. Grass continuously grows at each grid location, sheep wander around and eat some of the grass, and wolves wander around and eat sheep. Sheep and wolves both reproduce at some regular rate, and both die eventually if they don't have enough to eat. Parameters control the rates of grass growth, the initial numbers of sheep and wolves, the rates of sheep and wolf reproduction, and how much energy sheep and wolves derive from eating grass and sheep. These parameters can be set to produce a balanced model in which the current quantities of grass, sheep and wolves oscilate up and down but never drop to zero or increase without limit.

This Xholon application is based directly on the NetLogo model. As much as possible, it uses a Javaized version of the exact syntax found in the NetLogo original. The purpose of this is to demonstrate how Xholon can support the turtle geometry, Logo, StarLogo, and NetLogo paradigm.

How to use it

Things to notice

Things to try

Extending the model

Xholon features

This Xholon application demonstrates how to use the NetLogo-like turtle API.

Credits and references

The original NetLogo copyright notice is repeated below.

The same model has also been implemented using Repast: Tatara, E., North, M.J., Howe, T.R., Collier, N.T., Vos, J.R. (2006). An introduction to Repast Simphony modeling using a simple predator-prey example. repast.sourceforge.net/papers/Agent_2006_Repast_Tutorial.pdf

; *** NetLogo 3.1.3 Model Copyright Notice *** ; ; This model was created as part of the project: CONNECTED MATHEMATICS: ; MAKING SENSE OF COMPLEX PHENOMENA THROUGH BUILDING OBJECT-BASED PARALLEL ; MODELS (OBPML). The project gratefully acknowledges the support of the ; National Science Foundation (Applications of Advanced Technologies ; Program) -- grant numbers RED #9552950 and REC #9632612. ; ; Copyright 1998 by Uri Wilensky. All rights reserved. ; ; Permission to use, modify or redistribute this model is hereby granted, ; provided that both of the following requirements are followed: ; a) this copyright notice is included. ; b) this model will not be redistributed for profit without permission ; from Uri Wilensky. ; Contact Uri Wilensky for appropriate licenses for redistribution for ; profit. ; ; This model was converted to NetLogo as part of the projects: ; PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING ; IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. ; The project gratefully acknowledges the support of the ; National Science Foundation (REPP & ROLE programs) -- ; grant numbers REC #9814682 and REC-0126227. ; Converted from StarLogoT to NetLogo, 2000. ; ; To refer to this model in academic publications, please use: ; Wilensky, U. (1998). NetLogo Wolf Sheep Predation model. ; http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation. ; Center for Connected Learning and Computer-Based Modeling, ; Northwestern University, Evanston, IL. ; ; In other publications, please use: ; Copyright 1998 Uri Wilensky. All rights reserved. ; See http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation ; for terms of use. ; ; *** End of NetLogo 3.1.3 Model Copyright Notice ***