eckity.breeders.simple_breeder

 1from eckity.breeders.breeder import Breeder
 2from eckity.genetic_operators.selections.elitism_selection import ElitismSelection
 3
 4
 5class SimpleBreeder(Breeder):
 6	def __init__(self,
 7				 events=None):
 8		super().__init__(events=events)
 9		self.selected_individuals = []  # TODO why do we need this field? what about applied_individuals?
10		self.best_of_run = []  # TODO this field isn't used
11
12	def apply_breed(self, population):
13		"""
14		Apply elitism, selection method and the sub-population's operator sequence on each sub-population.
15		In simple case, the operator sequence is applied on the one and only sub-population.
16
17		Parameters
18		----------
19		population:
20			Population of sub-populations of individuals. The operators will be applied on those individuals.
21
22		Returns
23		-------
24		None.
25		"""
26		for subpopulation in population.sub_populations:
27			nextgen_population = []
28
29			num_elites = subpopulation.n_elite
30			if num_elites > 0:
31				elitism_sel = ElitismSelection(num_elites=num_elites, higher_is_better=subpopulation.higher_is_better)
32				elitism_sel.apply_operator((subpopulation.individuals, nextgen_population))
33
34			self.selected_individuals = subpopulation.get_selection_methods()[0][0] \
35				.select(subpopulation.individuals, nextgen_population)
36
37			# then runs all operators on next_gen
38			nextgen_population = self._apply_operators(subpopulation.get_operators_sequence(),
39													   self.selected_individuals)
40			# TODO assert simple operators the has %0 with pop size
41
42			subpopulation.individuals = nextgen_population
43
44	def _apply_operators(self, operator_seq, individuals_to_apply_on):
45		"""
46		Apply a given operator sequence on a given list of individuals.
47		The operators are done sequentially.
48
49		Parameters
50		----------
51		operator_seq: list of operators
52			Operator sequence. The operators will be applied sequentially on the given individuals.
53		individuals_to_apply_on: list of individuals
54			The individuals to apply the operator sequence on.
55
56		Returns
57		-------
58		list of individuals
59			The individuals list after the operators were applied on them.
60		"""
61		for operator in operator_seq:
62			operator_arity = operator.get_operator_arity()
63			for i in range(0, len(individuals_to_apply_on), operator_arity):
64				op_res = operator.apply_operator(individuals_to_apply_on[i:i + operator_arity])
65				individuals_to_apply_on[i:i + operator_arity] = op_res
66		return individuals_to_apply_on
67
68	def event_name_to_data(self, event_name):
69		if event_name == "after_selection":
70			return {"selected_individuals": self.selected_individuals,
71					"best_of_run": self.best_of_run}