# Cellular Automata¶

## Question¶

This generates a beautiful cellular automata pattern, following the rules of cellular automata evolution.

## Solution¶

```#!/usr/bin/env python
"""
CellularAutomata.py: Wolfram-style cellular automata in Python

Options:
-h #  Use a screen of height # for the simulation
-w #  Use a screen of width # for the simulation
-r      Use a random initial row (rather than the standard single 1 in the middle)
-R #  Use rule # for the simulation

Requires python-image (PIL package) installed.
Fills up an initial cell and runs a particular rule of Cellular Automata.

*I can't remember the source, if you claim/know, please inform.*

"""

import getopt,sys
from random import randint

def ca_data(height,width,dorandom,rulenum):
# Create the first row, either randomly, or with a single 1
if dorandom:
first_row = [randint(0,1) for i in range(width)]
else:
first_row = *width
first_row[width/2] = 1
results = [first_row]

# Convert the rule number to a list of outcomes.
rule = [(rulenum/pow(2,i)) % 2 for i in range(8)]

for i in range(height-1):
data = results[-1]
# Determine the new row based on the old data. We first make an
#  integer out of the value of the old row and its two neighbors
#  and then use that value to get the outcome from the table we
#  computed earlier
new = [rule[4*data[(j-1)%width]+2*data[j]+data[(j+1)%width]]
for j in range(width)]
results.append(new)
return results

def pil_render(data,height,width,fname="bs.png"):
import Image, ImageDraw
img = Image.new("RGB",(width,height),(255,255,255))
draw = ImageDraw.Draw(img)

for y in range(height):
for x in range(width):
if data[y][x]: draw.point((x,y),(0,0,0))
img.save(fname,"PNG")
return

def main():
opts,args = getopt.getopt(sys.argv[1:],'h:w:rR:')
height = 500
width = 500
dorandom = 0
rule = 22
for key,val in opts:
if key == '-h': height = int(val)
if key == '-w': width = int(val)
if key == '-r': dorandom = 1
if key == '-R': rule = int(val)
data = ca_data(height,width,dorandom,rule)
pil_render(data,height,width)
return

if __name__ == '__main__': main()
```