aliens - try

aliens.py

import random
from collections import defaultdict

from pprint import pprint

class City(object):
    def __init__(self, data=None):
        self.name = None
        self.neighbors = {}
        if data is not None:
            self.load(data) 

    def load(self, data):
        data=data.strip().split()
        self.name = data[0]
        for path in data[1:]:
            direction, city_name = path.split('=')
            self.neighbors[direction] = city_name
    
    def random_neighbor(self):
        if not self.neighbors:
            return None
        return random.choice(list(self.neighbors.values()))

    def __repr__(self):
        return 'City ({}) -> routes to: {} )'.format(self.name,
                ', '.join(self.neighbors.values()))

    def delete_route(self, neighbor):
        self.neighbors = {d:n for d,n in self.neighbors.items() 
                        if n != neighbor}

class World(object):
    def __init__(self, aliens = 10):

        self.cities = self.load_cities()
        self.load_aliens(aliens)

    def load_cities(self, fn = 'cities.txt'):
        city_map = {}
        with open(fn, mode='r') as fh:
            count = 0
            for line in fh:
                count += 1
                if count > 10:
                    pass
                city = City(line)
                city_map[city.name] = city
        return(city_map)

    def load_aliens(self, pop_cap):
        self.alien_map = defaultdict(list)
        for i in range(pop_cap):
            city = self.random_city()
            self.alien_map[city].append(i)

    def random_city(self):
        '''
        return a random city
        '''
        return random.choice(list(self.cities))
    
    def move_aliens(self):
        any_moved = False
        new_map = defaultdict(list)
        for city_name, aliens in self.alien_map.items():
            city = self.cities[city_name]
            for alien in aliens:
                new_city_name = city.random_neighbor()
                if new_city_name is None:
                    new_city_name = city_name
                else:
                    any_moved = True
                new_map[new_city_name].append(alien)
        self.alien_map = new_map
        return any_moved

    def delete_city(self, city_name):
        city = self.cities[city_name]
        neighbors = city.neighbors.values()
        for neighbor in map(self.cities.get,neighbors):
            neighbor.delete_route(city_name)
        del self.cities[city_name]

    def fight(self):
        new_map = {}
        for city_name, aliens in self.alien_map.items():
            if len(aliens)<=1:
                new_map[city_name] = aliens
                continue
            print('aliens {} fought at {}'.format(aliens, city_name))
            self.delete_city(city_name)
        self.alien_map = new_map







def main():
    world = World(4000)
    counter =0 
    while world.move_aliens():
        counter += 1
        world.fight()
        if counter > 10000:
            print('ran otu of time')
            break

    for city, aliens in world.alien_map.items():
        print(aliens, world.cities[city])


if __name__=='__main__':
    main()