class Agent(Thing):\n", " """An Agent is a subclass of Thing with one required slot,\n", " .program, which should hold a function that takes one argument, the\n", " percept, and returns an action. (What counts as a percept or action\n", " will depend on the specific environment in which the agent exists.)\n", " Note that 'program' is a slot, not a method. If it were a method,\n", " then the program could 'cheat' and look at aspects of the agent.\n", " It's not supposed to do that: the program can only look at the\n", " percepts. An agent program that needs a model of the world (and of\n", " the agent itself) will have to build and maintain its own model.\n", " There is an optional slot, .performance, which is a number giving\n", " the performance measure of the agent in its environment."""\n", "\n", " def __init__(self, program=None):\n", " self.alive = True\n", " self.bump = False\n", " self.holding = []\n", " self.performance = 0\n", " if program is None or not isinstance(program, collections.Callable):\n", " print("Can't find a valid program for {}, falling back to default.".format(\n", " self.__class__.__name__))\n", "\n", " def program(percept):\n", " return eval(input('Percept={}; action? '.format(percept)))\n", "\n", " self.program = program\n", "\n", " def can_grab(self, thing):\n", " """Return True if this agent can grab this thing.\n", " Override for appropriate subclasses of Agent and Thing."""\n", " return False\n", "

class Environment:\n",
       "    """Abstract class representing an Environment. 'Real' Environment classes\n",
       "    inherit from this. Your Environment will typically need to implement:\n",
       "        percept:           Define the percept that an agent sees.\n",
       "        execute_action:    Define the effects of executing an action.\n",
       "                           Also update the agent.performance slot.\n",
       "    The environment keeps a list of .things and .agents (which is a subset\n",
       "    of .things). Each agent has a .performance slot, initialized to 0.\n",
       "    Each thing has a .location slot, even though some environments may not\n",
       "    need this."""\n",
       "\n",
       "    def __init__(self):\n",
       "        self.things = []\n",
       "        self.agents = []\n",
       "\n",
       "    def thing_classes(self):\n",
       "        return []  # List of classes that can go into environment\n",
       "\n",
       "    def percept(self, agent):\n",
       "        """Return the percept that the agent sees at this point. (Implement this.)"""\n",
       "        raise NotImplementedError\n",
       "\n",
       "    def execute_action(self, agent, action):\n",
       "        """Change the world to reflect this action. (Implement this.)"""\n",
       "        raise NotImplementedError\n",
       "\n",
       "    def default_location(self, thing):\n",
       "        """Default location to place a new thing with unspecified location."""\n",
       "        return None\n",
       "\n",
       "    def exogenous_change(self):\n",
       "        """If there is spontaneous change in the world, override this."""\n",
       "        pass\n",
       "\n",
       "    def is_done(self):\n",
       "        """By default, we're done when we can't find a live agent."""\n",
       "        return not any(agent.is_alive() for agent in self.agents)\n",
       "\n",
       "    def step(self):\n",
       "        """Run the environment for one time step. If the\n",
       "        actions and exogenous changes are independent, this method will\n",
       "        do. If there are interactions between them, you'll need to\n",
       "        override this method."""\n",
       "        if not self.is_done():\n",
       "            actions = []\n",
       "            for agent in self.agents:\n",
       "                if agent.alive:\n",
       "                    actions.append(agent.program(self.percept(agent)))\n",
       "                else:\n",
       "                    actions.append("")\n",
       "            for (agent, action) in zip(self.agents, actions):\n",
       "                self.execute_action(agent, action)\n",
       "            self.exogenous_change()\n",
       "\n",
       "    def run(self, steps=1000):\n",
       "        """Run the Environment for given number of time steps."""\n",
       "        for step in range(steps):\n",
       "            if self.is_done():\n",
       "                return\n",
       "            self.step()\n",
       "\n",
       "    def list_things_at(self, location, tclass=Thing):\n",
       "        """Return all things exactly at a given location."""\n",
       "        return [thing for thing in self.things\n",
       "                if thing.location == location and isinstance(thing, tclass)]\n",
       "\n",
       "    def some_things_at(self, location, tclass=Thing):\n",
       "        """Return true if at least one of the things at location\n",
       "        is an instance of class tclass (or a subclass)."""\n",
       "        return self.list_things_at(location, tclass) != []\n",
       "\n",
       "    def add_thing(self, thing, location=None):\n",
       "        """Add a thing to the environment, setting its location. For\n",
       "        convenience, if thing is an agent program we make a new agent\n",
       "        for it. (Shouldn't need to override this.)"""\n",
       "        if not isinstance(thing, Thing):\n",
       "            thing = Agent(thing)\n",
       "        if thing in self.things:\n",
       "            print("Can't add the same thing twice")\n",
       "        else:\n",
       "            thing.location = location if location is not None else self.default_location(thing)\n",
       "            self.things.append(thing)\n",
       "            if isinstance(thing, Agent):\n",
       "                thing.performance = 0\n",
       "                self.agents.append(thing)\n",
       "\n",
       "    def delete_thing(self, thing):\n",
       "        """Remove a thing from the environment."""\n",
       "        try:\n",
       "            self.things.remove(thing)\n",
       "        except ValueError as e:\n",
       "            print(e)\n",
       "            print("  in Environment delete_thing")\n",
       "            print("  Thing to be removed: {} at {}".format(thing, thing.location))\n",
       "            print("  from list: {}".format([(thing, thing.location) for thing in self.things]))\n",
       "        if thing in self.agents:\n",
       "            self.agents.remove(thing)\n",
       "

Percept:	Feel Food	Feel Water	Feel Nothing
Action:	eat	drink	move down