Day & Night

Day & Night preview image

1 collaborator

Default-person David Weintrop (Author)


cellular automata 

Tagged by David Weintrop about 4 years ago

Visible to everyone | Changeable by everyone
Model was written in NetLogo 5.2.0 • Viewed 195 times • Downloaded 6 times • Run 0 times
Download the 'Day & Night' modelDownload this modelEmbed this model

Do you have questions or comments about this model? Ask them here! (You'll first need to log in.)


This program is an example of a two-dimensional cellular automaton. This particular cellular automaton is called The Game of Life.

A cellular automaton is a computational machine that performs actions based on certain rules. It can be thought of as a board which is divided into cells (such as square cells of a checkerboard). Each cell can be either "alive" or "dead." This is called the "state" of the cell. According to specified rules, each cell will be alive or dead at the next time step.

for info go here:


The rules of the game are as follows. Each cell checks the state of itself and its eight surrounding neighbors and then sets itself to either alive or dead. If there are less than two alive neighbors, then the cell dies. If there are more than three alive neighbors, the cell dies. If there are 2 alive neighbors, the cell remains in the state it is in. If there are exactly three alive neighbors, the cell becomes alive. This is done in parallel and continues forever.

There are certain recurring shapes in Life, for example, the "glider" and the "blinker". The glider is composed of 5 cells which form a small arrow-headed shape, like this:




This glider will wiggle across the world, retaining its shape. A blinker is a block of three cells (either up and down or left and right) that rotates between horizontal and vertical orientations.


The INITIAL-DENSITY slider determines the initial density of cells that are alive. SETUP-RANDOM places these cells. GO-FOREVER runs the rule forever. GO-ONCE runs the rule once.

If you want to draw your own pattern, use the DRAW-CELLS button and then use the mouse to "draw" and "erase" in the view.


Find some objects that are alive, but motionless.

Is there a "critical density" - one at which all change and motion stops/eternal motion begins?


Are there any recurring shapes other than gliders and blinkers?

Build some objects that don't die (using DRAW-CELLS)

How much life can the board hold and still remain motionless and unchanging? (use DRAW-CELLS)

The glider gun is a large conglomeration of cells that repeatedly spits out gliders. Find a "glider gun" (very, very difficult!).


Give some different rules to life and see what happens.

Experiment with using neighbors4 instead of neighbors (see below).


The neighbors primitive returns the agentset of the patches to the north, south, east, west, northeast, northwest, southeast, and southwest. So `count neighbors with [living?]` counts how many of those eight patches have the `living?` patch variable set to true.

`neighbors4` is like `neighbors` but only uses the patches to the north, south, east, and west. Some cellular automata, like this one, are defined using the 8-neighbors rule, others the 4-neighbors.


Life Turtle-Based --- same as this, but implemented using turtles instead of patches, for a more attractive display

CA 1D Elementary --- a model that shows all 256 possible simple 1D cellular automata

CA 1D Totalistic --- a model that shows all 2,187 possible 1D 3-color totalistic cellular automata

CA 1D Rule 30 --- the basic rule 30 model

CA 1D Rule 30 Turtle --- the basic rule 30 model implemented using turtles

CA 1D Rule 90 --- the basic rule 90 model

CA 1D Rule 110 --- the basic rule 110 model

CA 1D Rule 250 --- the basic rule 250 model


The Game of Life was invented by John Horton Conway.

See also:

Von Neumann, J. and Burks, A. W., Eds, 1966. Theory of Self-Reproducing Automata. University of Illinois Press, Champaign, IL.

"LifeLine: A Quarterly Newsletter for Enthusiasts of John Conway's Game of Life", nos. 1-11, 1971-1973.

Martin Gardner, "Mathematical Games: The fantastic combinations of John Conway's new solitaire game `life',", Scientific American, October, 1970, pp. 120-123.

Martin Gardner, "Mathematical Games: On cellular automata, self-reproduction, the Garden of Eden, and the game `life',", Scientific American, February, 1971, pp. 112-117.

Berlekamp, Conway, and Guy, Winning Ways for your Mathematical Plays, Academic Press: New York, 1982.

William Poundstone, The Recursive Universe, William Morrow: New York, 1985.


If you mention this model in an academic publication, we ask that you include these citations for the model itself and for the NetLogo software:

- Wilensky, U. (1998). NetLogo Life model. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

- Wilensky, U. (1999). NetLogo. 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 for terms of use.


Copyright 1998 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 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.

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, 2001.

Comments and Questions

Please start the discussion about this model! (You'll first need to log in.)

Click to Run Model

patches-own [
  living?         ;; indicates if the cell is living
  live-neighbors  ;; counts how many neighboring cells are alive

to setup-blank
  ask patches [ cell-death ]

to setup-random
  ask patches
    [ ifelse random-float 100.0 < initial-density
      [ cell-birth ]
      [ cell-death ] ]

to cell-birth
  set living? true
  set pcolor fgcolor

to cell-death
  set living? false
  set pcolor bgcolor

to go
  ask patches
    [ set live-neighbors count neighbors with [living?] ]
  ;; Starting a new "ask patches" here ensures that all the patches
  ;; finish executing the first ask before any of them start executing
  ;; the second ask.  This keeps all the patches in synch with each other,
  ;; so the births and deaths at each generation all happen in lockstep.
  ask patches
      ifelse (not living?) and (member? live-neighbors [3 6 7 8])
      [ cell-birth ]
      [ if (living?) and (member? live-neighbors [0 1 2 5])
        [ cell-death ] ] ]

to invert
  ask patches
    ifelse living?
    [cell-birth] ]

to draw-cells
  let erasing? [living?] of patch mouse-xcor mouse-ycor
  while [mouse-down?]
    [ ask patch mouse-xcor mouse-ycor
      [ ifelse erasing?
        [ cell-death ]
        [ cell-birth ] ]
      display ]

There are 2 versions of this model.

Uploaded by When Description Download
David Weintrop about 4 years ago updating Info tab Download this version
David Weintrop about 4 years ago Initial upload Download this version

Attached files

File Type Description Last updated
Day & Night.png preview preview image about 4 years ago, by David Weintrop Download

This model does not have any ancestors.

This model does not have any descendants.