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"""
Implement Agents and Environments. (Chapters 1-2)
The class hierarchies are as follows::
Thing ## A physical object that can exist in an environment
Agent
Wumpus
Dirt
Wall
...
Environment ## An environment holds objects, runs simulations
XYEnvironment
VacuumEnvironment
WumpusEnvironment
An agent program is a callable instance, taking percepts and choosing actions::
SimpleReflexAgentProgram
...
The GUI helpers are::
EnvGUI ## A window with a graphical representation of the Environment
EnvToolbar ## contains buttons for controlling EnvGUI
EnvCanvas ## Canvas to display the environment of an EnvGUI
"""
# TODO
# Speed control in GUI does not have any effect -- fix it.
from aima.utils import distance_squared, turn_heading
from statistics import mean
from IPython.display import HTML, display, clear_output
from time import sleep
import random
import copy
import collections
import numbers
# ______________________________________________________________________________
class Thing:
"""This represents any physical object that can appear in an Environment.
You subclass Thing to get the things you want. Each thing can have a
.__name__ slot (used for output only)."""
def __repr__(self):
return '<{}>'.format(getattr(self, '__name__', self.__class__.__name__))
def is_alive(self):
"""Things that are 'alive' should return true."""
return hasattr(self, 'alive') and self.alive
def show_state(self):
"""Display the agent's internal state. Subclasses should override."""
print("I don't know how to show_state.")
def display(self, canvas, x, y, width, height):
"""Display an image of this Thing on the canvas."""
# Do we need this?
pass
class Agent(Thing):
"""An Agent is a subclass of Thing with one required instance attribute
(aka slot), .program, which should hold a function that takes one argument,
the percept, and returns an action. (What counts as a percept or action
will depend on the specific environment in which the agent exists.)
Note that 'program' is a slot, not a method. If it were a method, then the
program could 'cheat' and look at aspects of the agent. It's not supposed
to do that: the program can only look at the percepts. An agent program
that needs a model of the world (and of the agent itself) will have to
build and maintain its own model. There is an optional slot, .performance,
which is a number giving the performance measure of the agent in its
environment."""
def __init__(self, program=None):
self.alive = True
self.bump = False
self.holding = []
self.performance = 0
if program is None or not isinstance(program, collections.abc.Callable):
print("Can't find a valid program for {}, falling back to default.".format(self.__class__.__name__))
def program(percept):
return eval(input('Percept={}; action? '.format(percept)))
self.program = program
def can_grab(self, thing):
"""Return True if this agent can grab this thing.
Override for appropriate subclasses of Agent and Thing."""
return False
def TraceAgent(agent):
"""Wrap the agent's program to print its input and output. This will let
you see what the agent is doing in the environment."""
old_program = agent.program
def new_program(percept):
action = old_program(percept)
print('{} perceives {} and does {}'.format(agent, percept, action))
return action
agent.program = new_program
return agent
# ______________________________________________________________________________
def TableDrivenAgentProgram(table):
"""
[Figure 2.7]
This agent selects an action based on the percept sequence.
It is practical only for tiny domains.
To customize it, provide as table a dictionary of all
{percept_sequence:action} pairs.
"""
percepts = []
def program(percept):
percepts.append(percept)
action = table.get(tuple(percepts))
return action
return program
def RandomAgentProgram(actions):
"""An agent that chooses an action at random, ignoring all percepts.
>>> list = ['Right', 'Left', 'Suck', 'NoOp']
>>> program = RandomAgentProgram(list)
>>> agent = Agent(program)
>>> environment = TrivialVacuumEnvironment()
>>> environment.add_thing(agent)
>>> environment.run()
>>> environment.status == {(1, 0): 'Clean' , (0, 0): 'Clean'}
True
"""
return lambda percept: random.choice(actions)
# ______________________________________________________________________________
def SimpleReflexAgentProgram(rules, interpret_input):
"""
[Figure 2.10]
This agent takes action based solely on the percept.
"""
def program(percept):
state = interpret_input(percept)
rule = rule_match(state, rules)
action = rule.action
return action
return program
def ModelBasedReflexAgentProgram(rules, update_state, model):
"""
[Figure 2.12]
This agent takes action based on the percept and state.
"""
def program(percept):
program.state = update_state(program.state, program.action, percept, model)
rule = rule_match(program.state, rules)
action = rule.action
return action
program.state = program.action = None
return program
def rule_match(state, rules):
"""Find the first rule that matches state."""
for rule in rules:
if rule.matches(state):
return rule
# ______________________________________________________________________________
loc_A, loc_B = (0, 0), (1, 0) # The two locations for the Vacuum world
def RandomVacuumAgent():
"""Randomly choose one of the actions from the vacuum environment.
>>> agent = RandomVacuumAgent()
>>> environment = TrivialVacuumEnvironment()
>>> environment.add_thing(agent)
>>> environment.run()
>>> environment.status == {(1,0):'Clean' , (0,0) : 'Clean'}
True
"""
return Agent(RandomAgentProgram(['Right', 'Left', 'Suck', 'NoOp']))
def TableDrivenVacuumAgent():
"""Tabular approach towards vacuum world as mentioned in [Figure 2.3]
>>> agent = TableDrivenVacuumAgent()
>>> environment = TrivialVacuumEnvironment()
>>> environment.add_thing(agent)
>>> environment.run()
>>> environment.status == {(1,0):'Clean' , (0,0) : 'Clean'}
True
"""
table = {((loc_A, 'Clean'),): 'Right',
((loc_A, 'Dirty'),): 'Suck',
((loc_B, 'Clean'),): 'Left',
((loc_B, 'Dirty'),): 'Suck',
((loc_A, 'Dirty'), (loc_A, 'Clean')): 'Right',
((loc_A, 'Clean'), (loc_B, 'Dirty')): 'Suck',
((loc_B, 'Clean'), (loc_A, 'Dirty')): 'Suck',
((loc_B, 'Dirty'), (loc_B, 'Clean')): 'Left',
((loc_A, 'Dirty'), (loc_A, 'Clean'), (loc_B, 'Dirty')): 'Suck',
((loc_B, 'Dirty'), (loc_B, 'Clean'), (loc_A, 'Dirty')): 'Suck'}
return Agent(TableDrivenAgentProgram(table))
def ReflexVacuumAgent():
"""
[Figure 2.8]
A reflex agent for the two-state vacuum environment.
>>> agent = ReflexVacuumAgent()
>>> environment = TrivialVacuumEnvironment()
>>> environment.add_thing(agent)
>>> environment.run()
>>> environment.status == {(1,0):'Clean' , (0,0) : 'Clean'}
True
"""
def program(percept):
location, status = percept
if status == 'Dirty':
return 'Suck'
elif location == loc_A:
return 'Right'
elif location == loc_B:
return 'Left'
return Agent(program)
def ModelBasedVacuumAgent():
"""An agent that keeps track of what locations are clean or dirty.
>>> agent = ModelBasedVacuumAgent()
>>> environment = TrivialVacuumEnvironment()
>>> environment.add_thing(agent)
>>> environment.run()
>>> environment.status == {(1,0):'Clean' , (0,0) : 'Clean'}
True
"""
model = {loc_A: None, loc_B: None}
def program(percept):
"""Same as ReflexVacuumAgent, except if everything is clean, do NoOp."""
location, status = percept
model[location] = status # Update the model here
if model[loc_A] == model[loc_B] == 'Clean':
return 'NoOp'
elif status == 'Dirty':
return 'Suck'
elif location == loc_A:
return 'Right'
elif location == loc_B:
return 'Left'
return Agent(program)
# ______________________________________________________________________________
class Environment:
"""Abstract class representing an Environment. 'Real' Environment classes
inherit from this. Your Environment will typically need to implement::
percept: Define the percept that an agent sees.
execute_action: Define the effects of executing an action;
also update the agent.performance slot.
The environment keeps a list of .things and .agents (which is a subset
of .things). Each agent has a .performance slot, initialized to 0.
Each thing has a .location slot, even though some environments may not
need this."""
def __init__(self):
self.things = []
self.agents = []
def thing_classes(self):
"""Return the list of Thing subclasses that may appear in this environment."""
return [] # List of classes that can go into environment
def percept(self, agent):
"""Return the percept that the agent sees at this point. (Implement this.)"""
raise NotImplementedError
def execute_action(self, agent, action):
"""Change the world to reflect this action. (Implement this.)"""
raise NotImplementedError
def default_location(self, thing):
"""Default location to place a new thing with unspecified location."""
return None
def exogenous_change(self):
"""If there is spontaneous change in the world, override this."""
pass
def is_done(self):
"""By default, we're done when we can't find a live agent."""
return not any(agent.is_alive() for agent in self.agents)
def step(self):
"""Run the environment for one time step. If the
actions and exogenous changes are independent, this method will
do. If there are interactions between them, you'll need to
override this method."""
if not self.is_done():
actions = []
for agent in self.agents:
if agent.alive:
actions.append(agent.program(self.percept(agent)))
else:
actions.append("")
for (agent, action) in zip(self.agents, actions):
self.execute_action(agent, action)
self.exogenous_change()
def run(self, steps=1000):
"""Run the Environment for given number of time steps."""
for step in range(steps):
if self.is_done():
return
self.step()
def list_things_at(self, location, tclass=Thing):
"""Return all things exactly at a given location."""
if isinstance(location, numbers.Number):
return [thing for thing in self.things
if thing.location == location and isinstance(thing, tclass)]
return [thing for thing in self.things
if all(x == y for x, y in zip(thing.location, location)) and isinstance(thing, tclass)]
def some_things_at(self, location, tclass=Thing):
"""Return true if at least one of the things at location
is an instance of class tclass (or a subclass)."""
return self.list_things_at(location, tclass) != []
def add_thing(self, thing, location=None):
"""Add a thing to the environment, setting its location. For
convenience, if thing is an agent program we make a new agent
for it. (Shouldn't need to override this.)"""
if not isinstance(thing, Thing):
thing = Agent(thing)
if thing in self.things:
print("Can't add the same thing twice")
else:
thing.location = location if location is not None else self.default_location(thing)
self.things.append(thing)
if isinstance(thing, Agent):
thing.performance = 0
self.agents.append(thing)
def delete_thing(self, thing):
"""Remove a thing from the environment."""
try:
self.things.remove(thing)
except ValueError as e:
print(e)
print(" in Environment delete_thing")
print(" Thing to be removed: {} at {}".format(thing, thing.location))
print(" from list: {}".format([(thing, thing.location) for thing in self.things]))
if thing in self.agents:
self.agents.remove(thing)
class Direction:
"""A direction class for agents that want to move in a 2D plane.
Usage::
d = Direction("down")
# to change directions:
d = d + "right" or d = d + Direction.R # both do the same thing
Note that the argument to __add__ must be a string and not a Direction
object, and it can only be 'right' or 'left'."""
R = "right"
L = "left"
U = "up"
D = "down"
def __init__(self, direction):
self.direction = direction
def __add__(self, heading):
"""
>>> d = Direction('right')
>>> l1 = d.__add__(Direction.L)
>>> l2 = d.__add__(Direction.R)
>>> l1.direction
'up'
>>> l2.direction
'down'
>>> d = Direction('down')
>>> l1 = d.__add__('right')
>>> l2 = d.__add__('left')
>>> l1.direction == Direction.L
True
>>> l2.direction == Direction.R
True
"""
if self.direction == self.R:
return {
self.R: Direction(self.D),
self.L: Direction(self.U),
}.get(heading, None)
elif self.direction == self.L:
return {
self.R: Direction(self.U),
self.L: Direction(self.D),
}.get(heading, None)
elif self.direction == self.U:
return {
self.R: Direction(self.R),
self.L: Direction(self.L),
}.get(heading, None)
elif self.direction == self.D:
return {
self.R: Direction(self.L),
self.L: Direction(self.R),
}.get(heading, None)
def move_forward(self, from_location):
"""
>>> d = Direction('up')
>>> l1 = d.move_forward((0, 0))
>>> l1
(0, -1)
>>> d = Direction(Direction.R)
>>> l1 = d.move_forward((0, 0))
>>> l1
(1, 0)
"""
# get the iterable class to return
iclass = from_location.__class__
x, y = from_location
if self.direction == self.R:
return iclass((x + 1, y))
elif self.direction == self.L:
return iclass((x - 1, y))
elif self.direction == self.U:
return iclass((x, y - 1))
elif self.direction == self.D:
return iclass((x, y + 1))
class XYEnvironment(Environment):
"""This class is for environments on a 2D plane, with locations
labelled by (x, y) points, either discrete or continuous.
Agents perceive things within a radius. Each agent in the
environment has a .location slot which should be a location such
as (0, 1), and a .holding slot, which should be a list of things
that are held."""
def __init__(self, width=10, height=10):
super().__init__()
self.width = width
self.height = height
self.observers = []
# Sets iteration start and end (no walls).
self.x_start, self.y_start = (0, 0)
self.x_end, self.y_end = (self.width - 1, self.height - 1)
perceptible_distance = 1
def things_near(self, location, radius=None):
"""Return all things within radius of location."""
if radius is None:
radius = self.perceptible_distance
radius2 = radius * radius
return [(thing, radius2 - distance_squared(location, thing.location))
for thing in self.things if distance_squared(
location, thing.location) <= radius2]
def percept(self, agent):
"""By default, agent perceives things within a default radius."""
return self.things_near(agent.location)
def execute_action(self, agent, action):
"""Apply a motion or manipulation action for the agent. Supports turning
('TurnRight'/'TurnLeft'), moving one step ('Forward', setting agent.bump on
a collision), grabbing a grabbable thing at the agent's location ('Grab'),
and dropping the last held thing ('Release')."""
agent.bump = False
if action == 'TurnRight':
agent.direction += Direction.R
elif action == 'TurnLeft':
agent.direction += Direction.L
elif action == 'Forward':
agent.bump = self.move_to(agent, agent.direction.move_forward(agent.location))
elif action == 'Grab':
things = [thing for thing in self.list_things_at(agent.location) if agent.can_grab(thing)]
if things:
agent.holding.append(things[0])
print("Grabbing ", things[0].__class__.__name__)
self.delete_thing(things[0])
elif action == 'Release':
if agent.holding:
dropped = agent.holding.pop()
print("Dropping ", dropped.__class__.__name__)
self.add_thing(dropped, location=agent.location)
def default_location(self, thing):
"""Return a random inbounds location that contains no Obstacle."""
location = self.random_location_inbounds()
while self.some_things_at(location, Obstacle):
# we will find a random location with no obstacles
location = self.random_location_inbounds()
return location
def move_to(self, thing, destination):
"""Move a thing to a new location. Returns True on success or False if there is an Obstacle.
If thing is holding anything, they move with him."""
thing.bump = self.some_things_at(destination, Obstacle)
if not thing.bump:
thing.location = destination
for o in self.observers:
o.thing_moved(thing)
for t in thing.holding:
self.delete_thing(t)
self.add_thing(t, destination)
t.location = destination
return thing.bump
def add_thing(self, thing, location=None, exclude_duplicate_class_items=False):
"""Add things to the world. If (exclude_duplicate_class_items) then the item won't be
added if the location has at least one item of the same class."""
if location is None:
super().add_thing(thing)
elif self.is_inbounds(location):
if (exclude_duplicate_class_items and
any(isinstance(t, thing.__class__) for t in self.list_things_at(location))):
return
super().add_thing(thing, location)
def is_inbounds(self, location):
"""Checks to make sure that the location is inbounds (within walls if we have walls)"""
x, y = location
return not (x < self.x_start or x > self.x_end or y < self.y_start or y > self.y_end)
def random_location_inbounds(self, exclude=None):
"""Returns a random location that is inbounds (within walls if we have walls)"""
location = (random.randint(self.x_start, self.x_end),
random.randint(self.y_start, self.y_end))
if exclude is not None:
while location == exclude:
location = (random.randint(self.x_start, self.x_end),
random.randint(self.y_start, self.y_end))
return location
def delete_thing(self, thing):
"""Deletes thing, and everything it is holding (if thing is an agent)"""
if isinstance(thing, Agent):
del thing.holding
super().delete_thing(thing)
for obs in self.observers:
obs.thing_deleted(thing)
def add_walls(self):
"""Put walls around the entire perimeter of the grid."""
for x in range(self.width):
self.add_thing(Wall(), (x, 0))
self.add_thing(Wall(), (x, self.height - 1))
for y in range(1, self.height - 1):
self.add_thing(Wall(), (0, y))
self.add_thing(Wall(), (self.width - 1, y))
# Updates iteration start and end (with walls).
self.x_start, self.y_start = (1, 1)
self.x_end, self.y_end = (self.width - 1, self.height - 1)
def add_observer(self, observer):
"""Adds an observer to the list of observers.
An observer is typically an EnvGUI.
Each observer is notified of changes in move_to and add_thing,
by calling the observer's methods thing_moved(thing)
and thing_added(thing, loc)."""
self.observers.append(observer)
def turn_heading(self, heading, inc):
"""Return the heading to the left (inc=+1) or right (inc=-1) of heading."""
return turn_heading(heading, inc)
class Obstacle(Thing):
"""Something that can cause a bump, preventing an agent from
moving into the same square it's in."""
pass
class Wall(Obstacle):
"""An impassable Obstacle forming the boundary or interior walls of a grid."""
pass
# ______________________________________________________________________________
class GraphicEnvironment(XYEnvironment):
"""An XYEnvironment that visualises itself in a Jupyter notebook using an
ipythonblocks BlockGrid, colouring each cell according to the class of the
last thing placed there."""
def __init__(self, width=10, height=10, boundary=True, color={}, display=False):
"""Define all the usual XYEnvironment characteristics,
but initialise a BlockGrid for GUI too."""
super().__init__(width, height)
# imported lazily so the rest of aima.agents (and modules that import it,
# e.g. logic/csp) can be used without the optional ipythonblocks GUI dep
try:
from ipythonblocks import BlockGrid
except ImportError as e:
raise ImportError("GraphicEnvironment needs the optional 'ipythonblocks' "
"package; install it with `pip install ipythonblocks`.") from e
self.grid = BlockGrid(width, height, fill=(200, 200, 200))
if display:
self.grid.show()
self.visible = True
else:
self.visible = False
self.bounded = boundary
self.colors = color
def get_world(self):
"""Returns all the items in the world in a format
understandable by the ipythonblocks BlockGrid."""
result = []
x_start, y_start = (0, 0)
x_end, y_end = self.width, self.height
for x in range(x_start, x_end):
row = []
for y in range(y_start, y_end):
row.append(self.list_things_at((x, y)))
result.append(row)
return result
"""
def run(self, steps=1000, delay=1):
"" "Run the Environment for given number of time steps,
but update the GUI too." ""
for step in range(steps):
sleep(delay)
if self.visible:
self.reveal()
if self.is_done():
if self.visible:
self.reveal()
return
self.step()
if self.visible:
self.reveal()
"""
def run(self, steps=1000, delay=1):
"""Run the Environment for given number of time steps,
but update the GUI too."""
for step in range(steps):
self.update(delay)
if self.is_done():
break
self.step()
self.update(delay)
def update(self, delay=1):
"""Pause for delay seconds, then redraw the world in the GUI."""
sleep(delay)
self.reveal()
def reveal(self):
"""Display the BlockGrid for this world - the last thing to be added
at a location defines the location color."""
self.draw_world()
# wait for the world to update and
# apply changes to the same grid instead
# of making a new one.
clear_output(1)
self.grid.show()
self.visible = True
def draw_world(self):
"""Repaint the BlockGrid, colouring each occupied cell by the class of the
last thing at that location using the configured color mapping."""
self.grid[:] = (200, 200, 200)
world = self.get_world()
for x in range(0, len(world)):
for y in range(0, len(world[x])):
if len(world[x][y]):
self.grid[y, x] = self.colors[world[x][y][-1].__class__.__name__]
def conceal(self):
"""Hide the BlockGrid for this world"""
self.visible = False
display(HTML(''))
# ______________________________________________________________________________
# Continuous environment
class ContinuousWorld(Environment):
"""Model for Continuous World"""
def __init__(self, width=10, height=10):
super().__init__()
self.width = width
self.height = height
def add_obstacle(self, coordinates):
"""Add a PolygonObstacle defined by the given list of vertex coordinates."""
self.things.append(PolygonObstacle(coordinates))
class PolygonObstacle(Obstacle):
"""An Obstacle in a ContinuousWorld whose shape is a polygon described by a
list of vertex coordinates."""
def __init__(self, coordinates):
"""Coordinates is a list of tuples."""
super().__init__()
self.coordinates = coordinates
# ______________________________________________________________________________
# Vacuum environment
class Dirt(Thing):
"""A piece of dirt that a vacuum agent can clean up."""
pass
class VacuumEnvironment(XYEnvironment):
"""The environment of [Ex. 2.12]. Agent perceives dirty or clean,
and bump (into obstacle) or not; 2D discrete world of unknown size;
performance measure is 100 for each dirt cleaned, and -1 for
each turn taken."""
def __init__(self, width=10, height=10):
super().__init__(width, height)
self.add_walls()
def thing_classes(self):
"""Return the Thing/Agent classes that may populate the vacuum world."""
return [Wall, Dirt, ReflexVacuumAgent, RandomVacuumAgent,
TableDrivenVacuumAgent, ModelBasedVacuumAgent]
def percept(self, agent):
"""The percept is a tuple of ('Dirty' or 'Clean', 'Bump' or 'None').
Unlike the TrivialVacuumEnvironment, location is NOT perceived."""
status = ('Dirty' if self.some_things_at(
agent.location, Dirt) else 'Clean')
bump = ('Bump' if agent.bump else 'None')
return status, bump
def execute_action(self, agent, action):
"""Carry out the agent's action. 'Suck' removes dirt at the agent's location
and adds 100 to its performance; movement actions are delegated to the
XYEnvironment, and every action other than 'NoOp' costs 1 performance point."""
agent.bump = False
if action == 'Suck':
dirt_list = self.list_things_at(agent.location, Dirt)
if dirt_list != []:
dirt = dirt_list[0]
agent.performance += 100
self.delete_thing(dirt)
else:
super().execute_action(agent, action)
if action != 'NoOp':
agent.performance -= 1
class TrivialVacuumEnvironment(Environment):
"""This environment has two locations, A and B. Each can be Dirty
or Clean. The agent perceives its location and the location's
status. This serves as an example of how to implement a simple
Environment."""
def __init__(self):
super().__init__()
self.status = {loc_A: random.choice(['Clean', 'Dirty']),
loc_B: random.choice(['Clean', 'Dirty'])}
def thing_classes(self):
"""Return the Thing/Agent classes that may populate this vacuum world."""
return [Wall, Dirt, ReflexVacuumAgent, RandomVacuumAgent, TableDrivenVacuumAgent, ModelBasedVacuumAgent]
def percept(self, agent):
"""Returns the agent's location, and the location status (Dirty/Clean)."""
return agent.location, self.status[agent.location]
def execute_action(self, agent, action):
"""Change agent's location and/or location's status; track performance.
Score 10 for each dirt cleaned; -1 for each move."""
if action == 'Right':
agent.location = loc_B
agent.performance -= 1
elif action == 'Left':
agent.location = loc_A
agent.performance -= 1
elif action == 'Suck':
if self.status[agent.location] == 'Dirty':
agent.performance += 10
self.status[agent.location] = 'Clean'
def default_location(self, thing):
"""Agents start in either location at random."""
return random.choice([loc_A, loc_B])
# ______________________________________________________________________________
# The Wumpus World
class Gold(Thing):
"""The gold the explorer is trying to grab in the Wumpus World."""
def __eq__(self, rhs):
"""All Gold are equal"""
return rhs.__class__ == Gold
pass
class Bump(Thing):
"""Percept signalling that the explorer walked into a wall."""
pass
class Glitter(Thing):
"""Percept indicating that gold is in the explorer's current room."""
pass
class Pit(Thing):
"""A pit that kills the explorer if entered."""
pass
class Breeze(Thing):
"""Percept felt in rooms adjacent to a Pit."""
pass
class Arrow(Thing):
"""The single arrow the explorer can shoot to try to kill the wumpus."""
pass
class Scream(Thing):
"""Percept heard throughout the world when the wumpus is killed."""
pass
class Wumpus(Agent):
"""The wumpus: a monster that kills the explorer sharing its room."""
screamed = False
pass
class Stench(Thing):
"""Percept smelled in rooms adjacent to the Wumpus."""
pass
class Explorer(Agent):
"""The agent that explores the Wumpus World, seeking gold while avoiding
pits and the wumpus."""
holding = []
has_arrow = True
killed_by = ""
direction = Direction("right")
def can_grab(self, thing):
"""Explorer can only grab gold"""
return thing.__class__ == Gold
class WumpusEnvironment(XYEnvironment):
"""A grid implementation of the Wumpus World from Chapter 7: a cave of rooms
surrounded by walls, holding pits, the wumpus and gold, in which an Explorer
agent perceives stench, breeze, glitter, bump and scream."""
pit_probability = 0.2 # Probability to spawn a pit in a location. (From Chapter 7.2)
# Room should be 4x4 grid of rooms. The extra 2 for walls
def __init__(self, agent_program, width=6, height=6):
super().__init__(width, height)
self.init_world(agent_program)
def init_world(self, program):
"""Spawn items in the world based on probabilities from the book"""
"WALLS"
self.add_walls()
"PITS"
for x in range(self.x_start, self.x_end):
for y in range(self.y_start, self.y_end):
if random.random() < self.pit_probability:
self.add_thing(Pit(), (x, y), True)
self.add_thing(Breeze(), (x - 1, y), True)
self.add_thing(Breeze(), (x, y - 1), True)
self.add_thing(Breeze(), (x + 1, y), True)
self.add_thing(Breeze(), (x, y + 1), True)
"WUMPUS"
w_x, w_y = self.random_location_inbounds(exclude=(1, 1))
self.add_thing(Wumpus(lambda x: ""), (w_x, w_y), True)
self.add_thing(Stench(), (w_x - 1, w_y), True)
self.add_thing(Stench(), (w_x + 1, w_y), True)
self.add_thing(Stench(), (w_x, w_y - 1), True)
self.add_thing(Stench(), (w_x, w_y + 1), True)
"GOLD"
self.add_thing(Gold(), self.random_location_inbounds(exclude=(1, 1)), True)
"AGENT"
self.add_thing(Explorer(program), (1, 1), True)
def get_world(self, show_walls=True):
"""Return the items in the world"""
result = []
x_start, y_start = (0, 0) if show_walls else (1, 1)
if show_walls:
x_end, y_end = self.width, self.height
else:
x_end, y_end = self.width - 1, self.height - 1
for x in range(x_start, x_end):
row = []
for y in range(y_start, y_end):
row.append(self.list_things_at((x, y)))
result.append(row)
return result
def percepts_from(self, agent, location, tclass=Thing):
"""Return percepts from a given location,
and replaces some items with percepts from chapter 7."""
thing_percepts = {
Gold: Glitter(),
Wall: Bump(),
Wumpus: Stench(),
Pit: Breeze()}
"""Agents don't need to get their percepts"""
thing_percepts[agent.__class__] = None
"""Gold only glitters in its cell"""
if location != agent.location:
thing_percepts[Gold] = None
result = [thing_percepts.get(thing.__class__, thing) for thing in self.things
if thing.location == location and isinstance(thing, tclass)]
return result if len(result) else [None]
def percept(self, agent):
"""Return things in adjacent (not diagonal) cells of the agent.
Result format: [Left, Right, Up, Down, Center / Current location]"""
x, y = agent.location
result = []
result.append(self.percepts_from(agent, (x - 1, y)))
result.append(self.percepts_from(agent, (x + 1, y)))
result.append(self.percepts_from(agent, (x, y - 1)))
result.append(self.percepts_from(agent, (x, y + 1)))
result.append(self.percepts_from(agent, (x, y)))
"""The wumpus gives out a loud scream once it's killed."""
wumpus = [thing for thing in self.things if isinstance(thing, Wumpus)]
if len(wumpus) and not wumpus[0].alive and not wumpus[0].screamed: