Feature new DE algorithms

pymoo/algorithms/moo/gde3.py

@@ -0,0 +1,148 @@
+from pymoo.algorithms.moo.nsde import NSDE
+from pymoo.core.population import Population
+from pymoo.util.dominator import get_relation
+from pymoo.operators.survival.rank_and_crowding import RankAndCrowding
+
+
+# =========================================================================================================
+# Implementation
+# =========================================================================================================
+
+
+class GDE3(NSDE):
+
+    def __init__(self,
+                 pop_size=100,
+                 variant="DE/rand/1/bin",
+                 CR=0.5,
+                 F=None,
+                 gamma=1e-4,
+                 **kwargs):
+        """
+        GDE3 is an extension of DE to multi-objective problems using a mixed type survival strategy.
+        It is implemented in this version with the same constraint handling strategy of NSGA-II by default.
+
+        Derived algorithms GDE3-MNN and GDE3-2NN use by default survival RankAndCrowding with metrics 'mnn' and '2nn'.
+
+        For many-objective problems, try using NSDE-R, GDE3-MNN, or GDE3-2NN.
+
+        For Bi-objective problems, survival = RankAndCrowding(crowding_func='pcd') is very effective.
+
+        Kukkonen, S. & Lampinen, J., 2005. GDE3: The third evolution step of generalized differential evolution. 2005 IEEE congress on evolutionary computation, Volume 1, pp. 443-450.
+
+        Parameters
+        ----------
+        pop_size : int, optional
+            Population size. Defaults to 100.
+
+        sampling : Sampling, optional
+            Sampling strategy of pymoo. Defaults to LHS().
+
+        variant : str, optional
+            Differential evolution strategy. Must be a string in the format: "DE/selection/n/crossover", in which, n in an integer of number of difference vectors, and crossover is either 'bin' or 'exp'. Selection variants are:
+
+                - 'ranked'
+                - 'rand'
+                - 'best'
+                - 'current-to-best'
+                - 'current-to-best'
+                - 'current-to-rand'
+                - 'rand-to-best'
+
+            The selection strategy 'ranked' might be helpful to improve convergence speed without much harm to diversity. Defaults to 'DE/rand/1/bin'.
+
+        CR : float, optional
+            Crossover parameter. Defined in the range [0, 1]
+            To reinforce mutation, use higher values. To control convergence speed, use lower values.
+
+        F : iterable of float or float, optional
+            Scale factor or mutation parameter. Defined in the range (0, 2]
+            To reinforce exploration, use higher values; for exploitation, use lower values.
+
+        gamma : float, optional
+            Jitter deviation parameter. Should be in the range (0, 2). Defaults to 1e-4.
+
+        de_repair : str, optional
+            Repair of DE mutant vectors. Is either callable or one of:
+
+                - 'bounce-back'
+                - 'midway'
+                - 'rand-init'
+                - 'to-bounds'
+
+            If callable, has the form fun(X, Xb, xl, xu) in which X contains mutated vectors including violations, Xb contains reference vectors for repair in feasible space, xl is a 1d vector of lower bounds, and xu a 1d vector of upper bounds.
+            Defaults to 'bounce-back'.
+
+        mutation : Mutation, optional
+            Pymoo's mutation operator after crossover. Defaults to NoMutation().
+
+        repair : Repair, optional
+            Pymoo's repair operator after mutation. Defaults to NoRepair().
+
+        survival : Survival, optional
+            Pymoo's survival strategy.
+            Defaults to RankAndCrowding() with crowding distances ('cd').
+            In GDE3, the survival strategy is applied after a one-to-one comparison between child vector and corresponding parent when both are non-dominated by the other.
+        """
+
+        super().__init__(pop_size=pop_size,
+                         variant=variant,
+                         CR=CR,
+                         F=F,
+                         gamma=gamma,
+                         **kwargs)
+
+    def _advance(self, infills=None, **kwargs):
+
+        assert infills is not None, "This algorithms uses the AskAndTell interface thus 'infills' must to be provided."
+
+        # The individuals that are considered for the survival later and final survive
+        survivors = []
+
+        # now for each of the infill solutions
+        for k in range(len(self.pop)):
+
+            # Get the offspring an the parent it is coming from
+            off, parent = infills[k], self.pop[k]
+
+            # Check whether the new solution dominates the parent or not
+            rel = get_relation(parent, off)
+
+            # If indifferent we add both
+            if rel == 0:
+                survivors.extend([parent, off])
+
+            # If offspring dominates parent
+            elif rel == -1:
+                survivors.append(off)
+
+            # If parent dominates offspring
+            else:
+                survivors.append(parent)
+
+        # Create the population
+        survivors = Population.create(*survivors)
+
+        # Perform a survival to reduce to pop size
+        self.pop = self.survival.do(self.problem, survivors, n_survive=self.n_offsprings)
+
+
+class GDE3MNN(GDE3):
+
+    def __init__(self, pop_size=100, variant="DE/rand/1/bin", CR=0.5, F=None, gamma=0.0001, **kwargs):
+        survival = RankAndCrowding(crowding_func="mnn")
+        super().__init__(pop_size, variant, CR, F, gamma, survival=survival, **kwargs)
+
+
+class GDE32NN(GDE3):
+
+    def __init__(self, pop_size=100, variant="DE/rand/1/bin", CR=0.5, F=None, gamma=0.0001, **kwargs):
+        survival = RankAndCrowding(crowding_func="2nn")
+        super().__init__(pop_size, variant, CR, F, gamma, survival=survival, **kwargs)
+
+
+class GDE3PCD(GDE3):
+
+    def __init__(self, pop_size=100, variant="DE/rand/1/bin", CR=0.5, F=None, gamma=0.0001, **kwargs):
+        survival = RankAndCrowding(crowding_func="pcd")
+        super().__init__(pop_size, variant, CR, F, gamma, survival=survival, **kwargs)

pymoo/algorithms/moo/nsde.py

@@ -0,0 +1,105 @@
+from pymoo.algorithms.moo.nsga2 import NSGA2
+from pymoo.operators.sampling.lhs import LHS
+from pymoo.algorithms.soo.nonconvex.de import VariantDE
+from pymoo.operators.survival.rank_and_crowding import RankAndCrowding
+
+
+# =========================================================================================================
+# Implementation
+# =========================================================================================================
+
+
+class NSDE(NSGA2):
+
+    def __init__(self,
+                 pop_size=100,
+                 sampling=LHS(),
+                 variant="DE/rand/1/bin",
+                 CR=0.7,
+                 F=None,
+                 gamma=1e-4,
+                 de_repair="bounce-back",
+                 survival=RankAndCrowding(),
+                 **kwargs):
+        """
+        NSDE is an algorithm that combines that combines NSGA-II sorting and survival strategies 
+        to DE mutation and crossover.
+
+        For many-objective problems, try using NSDE-R, GDE3-MNN, or GDE3-2NN.
+
+        For Bi-objective problems, survival = RankAndCrowding(crowding_func='pcd') is very effective.
+
+        Parameters
+        ----------
+        pop_size : int, optional
+            Population size. Defaults to 100.
+
+        sampling : Sampling, optional
+            Sampling strategy of pymoo. Defaults to LHS().
+
+        variant : str, optional
+            Differential evolution strategy. Must be a string in the format: "DE/selection/n/crossover", in which, n in an integer of number of difference vectors, and crossover is either 'bin' or 'exp'. Selection variants are:
+
+                - "ranked'
+                - 'rand'
+                - 'best'
+                - 'current-to-best'
+                - 'current-to-best'
+                - 'current-to-rand'
+                - 'rand-to-best'
+
+            The selection strategy 'ranked' might be helpful to improve convergence speed without much harm to diversity. Defaults to 'DE/rand/1/bin'.
+
+        CR : float, optional
+            Crossover parameter. Defined in the range [0, 1]
+            To reinforce mutation, use higher values. To control convergence speed, use lower values.
+
+        F : iterable of float or float, optional
+            Scale factor or mutation parameter. Defined in the range (0, 2]
+            To reinforce exploration, use higher values; for exploitation, use lower values.
+
+        gamma : float, optional
+            Jitter deviation parameter. Should be in the range (0, 2). Defaults to 1e-4.
+
+        de_repair : str, optional
+            Repair of DE mutant vectors. Is either callable or one of:
+
+                - 'bounce-back'
+                - 'midway'
+                - 'rand-init'
+                - 'to-bounds'
+
+            If callable, has the form fun(X, Xb, xl, xu) in which X contains mutated vectors including violations, Xb contains reference vectors for repair in feasible space, xl is a 1d vector of lower bounds, and xu a 1d vector of upper bounds.
+            Defaults to 'bounce-back'.
+
+        mutation : Mutation, optional
+            Pymoo's mutation operator after crossover. Defaults to NoMutation().
+
+        repair : Repair, optional
+            Pymoo's repair operator after mutation. Defaults to NoRepair().
+
+        survival : Survival, optional
+            Pymoo's survival strategy.
+            Defaults to RankAndCrowding() with crowding distances ('cd').
+            In GDE3, the survival strategy is applied after a one-to-one comparison between child vector and corresponding parent when both are non-dominated by the other.
+        """
+
+        # Number of offsprings at each generation
+        n_offsprings = pop_size
+
+        # Mating
+        mating = VariantDE(variant=variant,
+                           CR=CR,
+                           F=F,
+                           gamma=gamma,
+                           de_repair=de_repair,
+                           **kwargs)
+
+        # Init from pymoo's NSGA2
+        super().__init__(pop_size=pop_size,
+                         sampling=sampling,
+                         mating=mating,
+                         survival=survival,
+                         eliminate_duplicates=None,
+                         n_offsprings=n_offsprings,
+                         **kwargs)

pymoo/algorithms/moo/nsder.py

@@ -0,0 +1,123 @@
+import numpy as np
+from pymoo.algorithms.moo.nsga3 import ReferenceDirectionSurvival
+from pymoo.operators.sampling.lhs import LHS
+from pymoo.util.misc import has_feasible
+from pymoo.algorithms.moo.nsde import NSDE
+
+# =========================================================================================================
+# Implementation
+# =========================================================================================================
+
+
+class NSDER(NSDE):
+
+    def __init__(self,
+                 ref_dirs,
+                 pop_size=100,
+                 variant="DE/rand/1/bin",
+                 CR=0.7,
+                 F=None,
+                 gamma=1e-4,
+                 **kwargs):
+        """
+        NSDE-R is an extension of NSDE to many-objective problems (Reddy & Dulikravich, 2019) using NSGA-III survival.
+
+        S. R. Reddy and G. S. Dulikravich, "Many-objective differential evolution optimization based on reference points: NSDE-R," Struct. Multidisc. Optim., vol. 60, pp. 1455-1473, 2019.
+
+        Parameters
+        ----------
+        ref_dirs : array like
+            The reference directions that should be used during the optimization.
+
+        pop_size : int, optional
+            Population size. Defaults to 100.
+
+        sampling : Sampling, optional
+            Sampling strategy of pymoo. Defaults to LHS().
+
+        variant : str, optional
+            Differential evolution strategy. Must be a string in the format: "DE/selection/n/crossover", in which, n in an integer of number of difference vectors, and crossover is either 'bin' or 'exp'. Selection variants are:
+
+                - "ranked'
+                - 'rand'
+                - 'best'
+                - 'current-to-best'
+                - 'current-to-best'
+                - 'current-to-rand'
+                - 'rand-to-best'
+
+            The selection strategy 'ranked' might be helpful to improve convergence speed without much harm to diversity. Defaults to 'DE/rand/1/bin'.
+
+        CR : float, optional
+            Crossover parameter. Defined in the range [0, 1]
+            To reinforce mutation, use higher values. To control convergence speed, use lower values.
+
+        F : iterable of float or float, optional
+            Scale factor or mutation parameter. Defined in the range (0, 2]
+            To reinforce exploration, use higher values; for exploitation, use lower values.
+
+        gamma : float, optional
+            Jitter deviation parameter. Should be in the range (0, 2). Defaults to 1e-4.
+
+        de_repair : str, optional
+            Repair of DE mutant vectors. Is either callable or one of:
+
+                - 'bounce-back'
+                - 'midway'
+                - 'rand-init'
+                - 'to-bounds'
+
+            If callable, has the form fun(X, Xb, xl, xu) in which X contains mutated vectors including violations, Xb contains reference vectors for repair in feasible space, xl is a 1d vector of lower bounds, and xu a 1d vector of upper bounds.
+            Defaults to 'bounce-back'.
+
+        mutation : Mutation, optional
+            Pymoo's mutation operator after crossover. Defaults to NoMutation().
+
+        repair : Repair, optional
+            Pymoo's repair operator after mutation. Defaults to NoRepair().
+
+        survival : Survival, optional
+            Pymoo's survival strategy.
+            Defaults to ReferenceDirectionSurvival().
+        """
+
+        self.ref_dirs = ref_dirs
+
+        if self.ref_dirs is not None:
+
+            if pop_size is None:
+                pop_size = len(self.ref_dirs)
+
+            if pop_size < len(self.ref_dirs):
+                print(
+                    f"WARNING: pop_size={pop_size} is less than the number of reference directions ref_dirs={len(self.ref_dirs)}.\n"
+                    "This might cause unwanted behavior of the algorithm. \n"
+                    "Please make sure pop_size is equal or larger than the number of reference directions. ")
+
+        if 'survival' in kwargs:
+            survival = kwargs['survival']
+            del kwargs['survival']
+        else:
+            survival = ReferenceDirectionSurvival(ref_dirs)
+
+        super().__init__(pop_size=pop_size,
+                         variant=variant,
+                         CR=CR,
+                         F=F,
+                         gamma=gamma,
+                         survival=survival,
+                         **kwargs)
+
+    def _setup(self, problem, **kwargs):
+
+        if self.ref_dirs is not None:
+            if self.ref_dirs.shape[1] != problem.n_obj:
+                raise Exception(
+                    "Dimensionality of reference points must be equal to the number of objectives: %s != %s" %
+                    (self.ref_dirs.shape[1], problem.n_obj))
+
+    def _set_optimum(self, **kwargs):
+        if not has_feasible(self.pop):
+            self.opt = self.pop[[np.argmin(self.pop.get("CV"))]]
+        else:
+            self.opt = self.survival.opt