def create_tree(root_id):
# odd numbers are ids of terminal nodes, the others are non-terminal nodes.
n1 = node.Node(root_id)
n2 = node.Node(2)
n3 = node.Node(1)
n4 = node.Node(3)
n5 = node.Node(5)
node.set_children(n1, [n2, n3])
node.set_children(n2, [n4, n5])
s = solution.Solution(n1)
solution.set_previous_fitness(s, root_id)
return s
def donate(self, recipient, cross_point, donor):
"""
Replace a sub-tree of the recipient with a donor
:param recipient: solution object. recipient of the MLPS-GP crossover.
:param cross_point: node object. a crossover point.
:param donor: node object. root node of subtree(donor's root).
:return: bool. if fitness is improved or not.
"""
stop = False
previous_fitness = recipient.previous_fitness
parent_node, index = cross_point
pre_node = parent_node.children[index]
# TODO: check if the pre_node and the donor is same sub-tree, if so, we don't have to check the fitness of the new solution.
parent_node.children[index] = donor.root
fitness = self.problem.fitness(recipient)
if previous_fitness >= fitness:
parent_node.children[index] = pre_node
solution.set_previous_fitness(recipient, previous_fitness)
else:
stop = True
return stop
def test_stop_improvement_with_shuffle(self):
root = self.s1.root
c1 = root.children[0]
c2 = root.children[1]
is_shuffle = True
flg2 = False
flg4 = False
for i in range(100):
improved = localsearch.stop_improvement(self.s1,
root,
self.problem,
is_shuffle=is_shuffle)
if i == 0:
self.assertEqual(improved, True)
if root.func_id == 2:
flg2 = True
node.set_id(root, self.root_id)
solution.set_previous_fitness(self.s1, self.root_id)
elif root.func_id == 4:
flg4 = True
node.set_id(root, self.root_id)
solution.set_previous_fitness(self.s1, self.root_id)
if flg2 and flg4:
break
self.assertEqual(flg2 and flg4, True)
improved = localsearch.stop_improvement(self.s1,
c1,
self.problem,
is_shuffle=is_shuffle)
self.assertEqual(improved, False)
improved = localsearch.stop_improvement(self.s1,
c2,
self.problem,
is_shuffle=is_shuffle)
self.assertEqual(improved, False)
def improve(target_solution, target_node, candidate_id, problem):
"""
Core function for local search.
Replace the old function with a new function and then revert it if fitness is not improved.
:param target_solution: solution object. target solution of local search.
:param target_node: node object. target node of the target solution.
:param candidate_id: int. ID of candidate function for local search.
:param problem: problem object. problem for calculation of fitness.
:return: bool. if improvement is success, return True.
"""
pre_id = target_node.func_id
node.set_id(target_node, candidate_id)
if target_solution.previous_fitness is None: # if the solution does not have previous fitness, calculate it.
pre_fit = problem.fitness(target_solution)
else:
pre_fit = target_solution.previous_fitness
new_fit = problem.fitness(target_solution) # check the fitness.
if pre_fit >= new_fit: # if it is not success, revert the function.
node.set_id(target_node, pre_id)
solution.set_previous_fitness(target_solution, pre_fit)
return False
else:
return True
def bihc(target_solution, node_list, fs_core):
"""
Best improvement hill climber (BIHC) function.
:param node_list: list of node object. candidate node list.
:param fs_core: function. search function for a target node.
:return: solution object.
"""
pre_node = None
while node_list:
ori_fit = target_solution.previous_fitness
best_fit = target_solution.previous_fitness
best_node = None
best_id = None
for target_node in node_list: # Try to find the best-improving target node and the function id.
ori_id = target_node.func_id
fs_core(target_solution, target_node)
if best_fit < target_solution.previous_fitness:
best_node = target_node
best_id = target_node.func_id
# the target solution is reverted to the original for the next iteration.
node.set_id(target_node, ori_id)
solution.set_previous_fitness(target_solution, ori_fit)
# If there is no improvement, end this local search.
if best_node is None:
break
# Otherwise, adopt the improvement to the solution.
node.set_id(best_node, best_id)
solution.set_previous_fitness(target_solution, best_fit)
if pre_node is not None:
node_list.append(pre_node)
node_list.remove(best_node) # remove the replaced node from candidate node list
pre_node = best_node
return target_solution
def fitness(self, target_solution_or_solutions):
"""
calculate the fitness of target solution(s)
:param target_solution_or_solutions: solution object or list of solution objects.
solution to calculate fitness.
:return: fitness or list of fitness.
"""
if isinstance(target_solution_or_solutions, Solution):
fitness = self._cal_fitness(target_solution=target_solution_or_solutions)
self._eval_cnt += 1
solution.set_previous_fitness(target_solution_or_solutions, fitness)
self._elite_fitness = max(self._elite_fitness, fitness)
return fitness
elif isinstance(target_solution_or_solutions, list):
fitness_list = []
for target_solution in target_solution_or_solutions:
fitness = self._cal_fitness(target_solution=target_solution)
solution.set_previous_fitness(target_solution, fitness)
fitness_list.append(fitness_list)
self._elite_fitness = max(self._elite_fitness, fitness)
self._eval_cnt += len(target_solution_or_solutions)
return fitness_list
else:
raise TypeError("target_solution_or_solutions should be Solution object or list of Solution objects.")
def get_population():
s1 = solution.Solution(node.Node())
s2 = solution.Solution(node.Node())
s3 = solution.Solution(node.Node())
solution.set_previous_fitness(s1, 1)
solution.set_previous_fitness(s2, 2)
solution.set_previous_fitness(s3, 3)
pop = []
for _ in range(2):
pop.extend([s1, s2, s3])
pop = pop * 2
return pop
def __init__(self):
self.population = []
self.n_set = 2
for i in range(self.n_set):
s1 = self.create_tree_type1()
s2 = self.create_tree_type2()
s3 = self.create_tree_type3()
solution.set_previous_fitness(s1, 1)
solution.set_previous_fitness(s2, 2)
solution.set_previous_fitness(s3, 3)
self.population.append(s1)
self.population.append(s2)
self.population.append(s3)
self.population = self.population * 2
