class MaxWalkSat:
def __init__(self, model = "Kursawe", probability = 0.5, no_steps = 10, baseline_top = -10**6, baseline_bottom = 10**6):
self.n = 6
self.p = probability
self.evals = 0
self.steps = no_steps
self.number_of_evaluations = 0
self.threshold = - 400
if model == "Osyczka":
self.model = Osyczka()
elif model == "Golinski":
self.model = Golinski()
elif model == "Kursawe":
self.model = Kursawe()
self.model.resetBaselines()
self.current_state = self.model.get_random_state()
def modify_to_better_state(self, state, index):
if(index > len(self.model.top_bound)):
return None
increment = (self.model.top_bound[index] - self.model.bottom_bound[index])/self.steps
temp_state = list(state)
best_state = state
for _ in range(0, self.steps):
temp_state[index] += increment
self.evals += 1
if self.model.energy(temp_state) < self.model.energy(best_state) and self.model.are_constraints_satisfied(temp_state):
best_state = list(temp_state)
state = best_state
return state
def retry(self, state):
index = randint(0, (self.model.getNumberOfDecisions() - 1))
temp_state = list(state)
if self.p < random():
#print self.model.bottom_bound[index]
#print self.model.top_bound[index]
temp_state[index] = self.model.bottom_bound[index] + (self.model.top_bound[index] - self.model.bottom_bound[index])*random()
if self.model.are_constraints_satisfied(temp_state):
return temp_state
else:
return state
else:
temp_state = self.modify_to_better_state(temp_state, index)
if temp_state == state:
return temp_state
else:
return temp_state
def run(self):
max_tries = 100
max_changes = 50
self.model.resetBaselines()
best_state = self.model.get_random_state()
output = str()
for _ in range(0, max_tries):
current_state = self.model.get_random_state()
for i in range(0, max_changes):
if self.model.energy(current_state) < self.threshold:
return current_state
else:
new_state = self.retry(current_state)
operation = ""
if self.model.energy(new_state) > self.model.energy(best_state):
best_state = new_state
operation = "!"
elif self.model.energy(new_state) > self.model.energy(current_state):
operation = "+"
elif self.model.energy(new_state) < self.model.energy(current_state):
operation = "."
output += operation
if len(output) == 50:
print output + " current best state energy(normalized) = " + str(self.model.energy(best_state)) + " Evaluations: " + str(self.evals)
output = ""
print output + " current best state energy(normalized) = " + str(self.model.aggregate_energy(best_state)) + " Evaluations: " + str(self.evals)
return best_state
