an algorithm implementation of simple dimentional cellular automaton

one-dimensional-cellular-automaton.py

# coding: utf-8
# one dimensional cell automaton

import random

class Cell1Dim(object):
    def __init__(self, rule, initializer):
        # buffer
        self.fore = initializer
        self.back = [0] * len(initializer)
        self.step = 0
        self.rule = [(rule >> (7-i)) & 1 for i in range(8)]
    def update(self):
        for i in xrange(len(self.fore)):
            j = (self[i-1]<<2) +  (self[i]<<1) +  self[i+1]
            self.back[i] = self.rule[j]
        self.fore = self.back[:]
        self.step += 1
    def __getitem__(self, i):
        return self.fore[(i + len(self.fore)) % len(self.fore)]
    def __repr__(self):
        return "".join([" *"[c] for c in self.fore])

def main():
    import sys, os
    if len(sys.argv) < 2:
        print 'usage: %s rule [turn]' % os.path.basename(__file__)
        return

    rule = None
    n = 30
    
    try:
        rule = int(sys.argv[1])
        assert 0 <= rule <= 255
    except:
        return
    
    if len(sys.argv) > 2:
        try:
            n = int(sys.argv[2])
            assert n >= 0
        except:
            print 'argument `turn\' must be non-negative integer'
            return
    
    a = Cell1Dim(rule, [random.randint(0,1) for i in range(80)])
    for i in range(n):
        print a
        a.update()

if __name__ == '__main__':
    main()