evolving_monkey.py

"""
License: MIT
Author: Heath Matlock
Problem: https://en.wikipedia.org/wiki/Weasel_program
"""
 
import string
import random
from time import time
 
class Typing_Monkey():
    def __init__(self):
        self.possible_choices = string.lowercase + ' '
        self.desired_list = list('methinks it is a weasel')
        self.prev_list_validity = []
 
    def gen_string(self, length):
        random_text = ''.join(random.choice(self.possible_choices) for _ in range(length))
        return random_text
     
    def check_validity(self, aList, desired_list):
        if len(self.prev_list_validity) != 0:
            # use assignment
            for index, char in enumerate(aList):
                if char == desired_list[index]:
                    self.prev_list_validity[index] = True
                else:
                    self.prev_list_validity[index] = False
        else:
            # use append
            for index, char in enumerate(aList):
                if char == desired_list[index]:
                    self.prev_list_validity.append(True)
                else:
                    self.prev_list_validity.append(False)

    def gen_orig_list(self):
        self.current_list = list(self.gen_string(len(self.desired_list)))

    def gen_new_list(self):
        new_list = []
        for index, char in enumerate(self.prev_list_validity):
            if char == True:
                try:
                    # should succeed after the first attempt, using current_list
                    new_list.append(self.current_list[index])
                except:
                    # should fall through the first attempt, using original_list
                    new_list.append(self.original_list[index])
            else:
                new_list.append(self.gen_string(1))
        self.current_list = new_list

    def bootstrap(self):
        self.gen_orig_list()
        self.check_validity(self.current_list, self.desired_list)

    def start_typing(self):
        starting_time = time()
        self.bootstrap()
        self.attempts = 1
        while self.current_list != self.desired_list:
            self.gen_new_list()
            self.check_validity(self.current_list, self.desired_list)
            self.attempts += 1
        ending_time = time()
        print "desired string: ", ''.join(self.desired_list)
        print "resulting string: ", ''.join(self.current_list)
        print "time elapsed: ", ending_time - starting_time
        print "number of attempts: ", self.attempts


#######################################################
# Go monkey go!
#######################################################
 
if __name__ == '__main__':
    typing_monkey = Typing_Monkey()
    typing_monkey.start_typing()