def __init__(self,h):
self.problem = BlocksWorld()
# start with an empty plan
self.plan = Plan()
# h is a "heuristic" object
self.h = h
def __init__(self,h):
self.problem = BlocksWorld()
# start with an empty plan
self.plan = Plan()
# h is a "heuristic" object
self.h=h
class ForwardSearch:
def __init__(self,h):
self.problem = BlocksWorld()
# start with an empty plan
self.plan = Plan()
# h is a "heuristic" object
self.h = h
def search(self):
import heapq
from state import State
from copy import deepcopy
def Heuristic(state, problem):
return self.h.heuristic(state, problem)
class PriorityQueue:
def __init__(self):
self.heap = []
self.count = 0
def push(self, item, priority):
# FIXME: restored old behaviour to check against old results better
# FIXED: restored to stable behaviour
entry = (priority, self.count, item)
# entry = (priority, item)
heapq.heappush(self.heap, entry)
self.count += 1
def pop(self):
(_, _, item) = heapq.heappop(self.heap)
# (_, item) = heapq.heappop(self.heap)
return item
def isEmpty(self):
return len(self.heap) == 0
class AllActions():
def __init__(self):
self.actions = []
def addAction(self, action):
self.actions.append(action)
return self
def getActions(self):
return self.actions
def getSuccessors(arg):
""" now arg is a tuple"""
actions = self.problem.getActions()
successors = []
for action in actions:
state = State(list(arg))
precondition = action.getPreconditions()
if state.entails(State(precondition)):
addList = action.getAddList()
deleteList = action.getDeleteList()
stateLiterals = state.getLiterals()
# delete literal from stateLiterals
for l1 in stateLiterals:
for l2 in deleteList:
if l2.equals(l1):
stateLiterals.remove(l1)
break
# add literal into stateLiterals
for l3 in addList:
for l1 in stateLiterals:
if l1.equals(l3):
break
else:
stateLiterals.append(l3)
succState = tuple(stateLiterals)
successors.append((succState, action, 1, Heuristic(succState, self.problem)))
return successors
def visitedState(state):
for k in Closed.keys():
visitedState = State(list(k))
if visitedState.equals(State(list(state))):
# Closed[k] is totalCost of state k in Closed
return (True, Closed[k])
return (False, None)
startState = tuple(self.problem.getInitialState().getLiterals())
Actions = AllActions()
fringe, Closed = PriorityQueue(), dict()
fringe.push((startState, Actions, 0, Heuristic(startState, self.problem)), 0 + Heuristic(startState, self.problem))
while not fringe.isEmpty():
toExpandState = fringe.pop()
if self.problem.reachedGoal(State(toExpandState[0])):
actions = toExpandState[1]
break
Closed[toExpandState[0]] = toExpandState[2] + Heuristic(toExpandState[0], self.problem)
for triple in getSuccessors(toExpandState[0]):
stepCost = toExpandState[2] + triple[2]
currentTotalCost = stepCost + Heuristic(triple[0], self.problem)
_visited, _cost = visitedState(triple[0])
if _visited and currentTotalCost >= _cost:
continue
triple = (triple[0], deepcopy(toExpandState[1]).addAction(triple[1]), stepCost, currentTotalCost)
fringe.push(triple, triple[3])
Closed[triple[0]] = triple[3]
self.plan.actions = actions.getActions()
# return the final plan
return self.plan
