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NetLogo Models Library:
Curricular Models/Urban Suite

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Urban Suite - Cells

[screen shot]

If you download the NetLogo application, this model is included. (You can also run this model in your browser, but we don't recommend it; details here.)

WHAT IS IT?

This is a model of 2d cellular automata. It uses very simple rules to grow a form. These forms may be very complex, or highly regular.

HOW IT WORKS

At each step, each patch looks to see if it satisfies the rules defined for being turned on. The rule is defined by the NEIGHBORHOOD chooser and the N-COUNT chooser. If the number of currently turned on patches in the NEIGHBORHOOD around the patch is non-zero and also satisfies N-COUNT, then that patch has a chance to turn. The change to turn on is defined by the PROBABILITY slider. If AGE-LIMIT is non-zero, then any patches that have been turned on for more ticks than AGE-LIMIT will be turned off.

The patches color shows their age, with darker patches being older than lighter patches.

HOW TO USE IT

Press SETUP to clear the board and create the initial seed patch. Optionally, you may also press the RANDOM SEED button to create another seed in a random location.

Press the GO * 80 button and the model will run thru 80 ticks. You may also press the STEP button to advance the model a single tick. Lastly, the GO button will run the model an unlimited number of ticks, until it is pressed again.

The NEIGHBORS and N-COUNT choosers define the rule used to determine if a patch turns on or not, see the HOW IT WORKS section for details.

PROBABILITY is the chance a patch has of turning on if it satisfies the current rule.

AGE-LIMIT is the number of ticks a patch will stay turned on. If AGE-LIMIT is 0, then there is no AGE-LIMIT defined and turned on patches stay that way forever.

The CYCLE COLORS button will make all turned on patches to cycle their colors.

The LIVE CELLS plot is a plot of the patches that are turned on at each tick.

THINGS TO NOTICE

Which rules produce the most complex shape?

How many ticks does it take for the rules to fill up the world?

THINGS TO TRY

Some rules will result in a form that grows and fills the whole space, while others will have empty spots in them.

If you play with the PROBABILITY slider you can get asymmetrical forms, and also cause "mutations" in the growth of a form that would otherwise stop growing after a set number of ticks. Such mutations can grow to fill in more patches because of the irregularity.

EXTENDING THE MODEL

Add new neighborhoods to the NEIGHBORHOODS chooser. You can do this by writing a reporter with the same name as your new neighborhood and adding the name to the chooser.

NETLOGO FEATURES

The scale-color primitive is used to set the color of patches according to their age.

RELATED MODELS

This model is related to all of the other models in the "Urban Suite".

This model is also similar to the models in the Computer Science/Cellular Automata section of the NetLogo models library.

CREDITS AND REFERENCES

This model is based from the models described in chapter 2 of the book "Cities and Complexity" by Michael Batty.

Thanks to Craig Brozefsky for his work on this model.

The Urban Suite models were developed as part of the Procedural Modeling of Cities project, under the sponsorship of NSF ITR award 0326542, Electronic Arts & Maxis.

Please see the project web site ( http://ccl.northwestern.edu/cities/ ) for more information.

HOW TO CITE

If you mention this model or the NetLogo software in a publication, we ask that you include the citations below.

For the model itself:

Please cite the NetLogo software as:

COPYRIGHT AND LICENSE

Copyright 2007 Uri Wilensky.

CC BY-NC-SA 3.0

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.

Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at uri@northwestern.edu.

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