README.md

cellular-automata

A python module for creating and visualizing multi-generational 2-dimensional cellular automata (CA).

Quickstart: Run Conway's Game of Life

from ca2d import CA 
ca = CA(100, 100)
ca.randomize()
ca.evolve()

Close the pygame window to quit.

Visualize a historical game

Unless save=False is passed to ca.evolve(), games are stored in CA.history. You can specify which historical game to use by index (ca.history[5]). By default, the most recent saved game is used.

from ca2d import CA 
ca = CA(100, 100)
ca.randomize()
ca.evolve(tick=0.1)

ca.animate()

Animation controls

• Use SPACE to play/pause
• When paused, use j/k to step forward/back
• Use r to reverse time
• Use 0 to jump to the beginning, and 1-9 to skip around.

What are multi-generational cellular automata?

There is a wonderful human named Mirek Wojtovicz who has done a lot of work to catalog and visualize lots of different types of cellular automata. His website is here: http://www.mirekw.com/

"Generations" is one of the many familites of CA rules that Mirek describes on his site. It's a simple extension of the familiar "Life" family of CAs which inclues Conway's Game of Life. Rather than transitioning from live to dead, cells enter a dying or refractory state where they are not counted as live cells but still take up space. This leads to highly dynamic evolution, often producing glider-like objects and other complex and aesthetically pleasing patters from shockingly simple rules.

Rules are encoded in strings with format 'S/B/G', where S = survival, B = birth, G = generations. Game of Life is encoded as 23/3/2. G = 2 because there are only two states: alive and dead.

I scraped Mirek's website for a table of notable "Generations" rules with names and descriptions. You can view it as a pandas dataframe with CA.rules_table.

Running a specific rule

You can pass a rule string or a rule name to the CA constructor.

ca = CA(100, 100, rule='345/2/4')

345/2/4 is the rule for "Star Wars", one of the coolest CAs I've ever seen. The following is equivalent:

ca = CA(100, 100, rule_name='Star Wars')

If both rule and rule_name are passed, rule_name is used.

Display methods

A display method is a method that takes a game (3d numpy array) and an index, and draws a pattern on the pygame display as a function of the game and index. Passing a list of display method names to display_methods in the animate() function will cause those display methods to be used in that order.

Right now, the only ones that work are "generations" and "memory". "generations" draws a different color for each generation. "memory" adds up the past n frames and draws varying shades of red corresponding to the number for each cell.

Cool Examples

Here are just a few examples of the incredible animations you can create with a multi-gen 2D CA and color map (a list of rgb tuples where the index corresponds to the state of the cell to which that color is assigned)

game of life with memory

from ca2d import CA
gol = CA(100, 100)
gol.randomize()
gol.evolve(limit=1000)
gol.animate(display_methods=['memory', 'generations'], colors=[CA.Black, (102, 102, 102)])

Brian's Brain with memory

from ca2d import CA
bb = CA(100, 100, rule_name='Brian\'s Brain')
bb.randomize()
bb.evolve(limit=500)
bb.animate(display_methods=['memory', 'generations'])

(Can you spot the Sierpinski triangles?)

Prairie on fire with fire colors

from ca2d import CA
pf = CA(100, 100, rule_name='Prairie on fire')
pf.randomize(option='square')
pf.evolve(limit=500)
pf.animate(colors=CA.fire_colors)

Meteor Guns

from ca2d import CA
mg = CA(100, 100, rule_name='Meteor Guns')
mg.randomize(option='square', size=5)
mg.evolve(limit=500)
mg.animate(colors=CA.fire_colors)