def mutate(self, parent: Tree):
if (self.mutation_algorithms is None) or (self.mutation_algorithms is
[]):
return
elif random.random() > self.mutation_rate:
return
rand_mutation_method: str = self.mutation_algorithms[random.randrange(
0, self.mutation_algorithms.__len__())]
# todo not sure about correct names for these types of mutations
if rand_mutation_method is "delete": # delete children underneath and attach random terminals to it
self.__mutate_delete(parent)
elif rand_mutation_method is "change": # change the label of the node with respect to its max_num_of_children
self.__mutate_change(parent)
elif rand_mutation_method is "add": # adds a whole new tree as one of its children
self.__mutate_add(parent)
elif rand_mutation_method is "exchange": # change the type (function to terminal and otherwise)
pass # todo implement this
else:
raise Exception("Invalid Algorithm for Mutation")
parent.is_mutated = True
parent.update_tree()
if parent.depth > self.max_depth:
parent.reshape_max_depth(self.max_depth)
def __cross_over(self, parent_1: Tree, parent_2: Tree) -> Tree:
# getting a random node from parent_2
temp_node = parent_2.get_random_node().copy()
# region generating a index range for parent_1
depth_min_range = hp.GP.cross_over_min_range
depth_max_range = int(hp.GP.cross_over_min_range_multiplier *
parent_1.number_of_nodes_in_tree)
if depth_min_range >= depth_max_range:
raise Exception("Invalid Range for crossover replacement : (",
depth_min_range, " , ", depth_max_range, ")")
if depth_max_range is 1:
depth_max_range += 1
depth_range = (depth_min_range, depth_max_range)
# endregion
parent_1.select_random_node_and_replace(depth_range, temp_node)
# update and reshape the tree if needed
parent_1.update_tree()
if parent_1.depth > self.max_depth:
parent_1.reshape_max_depth(self.max_depth)
return parent_1