def do(pop, n_survive):
# get the objective space values and objects
F = pop.get('F')
# the final indices of surviving individuals
survivors = []
# do the non-dominated sorting until splitting front
fronts = NonDominatedSorting().do(F, n_stop_if_ranked=n_survive)
for k, front in enumerate(fronts):
# calculate the crowding distance of the front
crowding_of_front = calc_crowding_distance(F[front, :])
# save rank and crowding in the individual class
for j, i in enumerate(front):
pop[i].set('rank', k)
pop[i].set('crowding', crowding_of_front[j])
# current front sorted by crowding distance if splitting
if len(survivors) + len(front) > n_survive:
I = randomized_argsort(crowding_of_front,
order='descending',
method='numpy')
I = I[:(n_survive - len(survivors))]
# otherwise take the whole front unsorted
else:
I = np.arange(len(front))
# extend the survivors by all or selected individuals
survivors.extend(front[I])
return pop[survivors]
def _do(self, pop, n_survive, D=None, **kwargs):
# attributes to be set after the survival
F = pop.get("F")
# find or usually update the new ideal point - from feasible solutions
self.ideal_point = np.min(np.vstack((self.ideal_point, F)), axis=0)
self.worst_point = np.max(np.vstack((self.worst_point, F)), axis=0)
# calculate the fronts of the population
fronts, rank = NonDominatedSorting().do(F,
return_rank=True,
n_stop_if_ranked=n_survive)
self.nadir_point = get_nadir_point_from_fronts(F, fronts,
self.ideal_point)
# consider only the population until we come to the splitting front
I = np.concatenate(fronts)
pop, rank, F = pop[I], rank[I], F[I]
# update the front indices for the current population
counter = 0
for i in range(len(fronts)):
for j in range(len(fronts[i])):
fronts[i][j] = counter
counter += 1
last_front = fronts[-1]
# associate individuals to niches
niche_of_individuals, dist_to_niche = associate_to_niches(
F, self.ref_dirs, self.ideal_point, self.nadir_point)
pop.set('rank', rank, 'niche', niche_of_individuals, 'dist_to_niche',
dist_to_niche)
# if we need to select individuals to survive
if len(pop) > n_survive:
# if there is only one front
if len(fronts) == 1:
n_remaining = n_survive
until_last_front = np.array([], dtype=np.int)
niche_count = np.zeros(len(self.ref_dirs), dtype=np.int)
# if some individuals already survived
else:
until_last_front = np.concatenate(fronts[:-1])
niche_count = calc_niche_count(
len(self.ref_dirs), niche_of_individuals[until_last_front])
n_remaining = n_survive - len(until_last_front)
S = niching(F[last_front, :], n_remaining, niche_count,
niche_of_individuals[last_front],
dist_to_niche[last_front])
survivors = np.concatenate(
(until_last_front, last_front[S].tolist()))
pop = pop[survivors]
return pop
def eval(self, problem=None, x=None, archive=None, **kwargs):
if x.ndim == 1:
n = 1
x = np.expand_dims(x, 0)
else:
n = x.shape[0]
f = np.zeros((n, problem.n_obj))
g = np.zeros((n, np.max([problem.n_constr, 1])))
if self.n_eval + x.shape[0] > self.n_max_eval:
rest = self.n_max_eval - self.n_eval
I = np.random.permutation(x.shape[0])
I = I[:rest]
x = x[I]
f = f[I]
g = g[I]
problem._evaluate_high_fidelity(x=x, f=f, g=g)
archive['x'] = np.concatenate((x, archive['x']), axis=0)
archive['f'] = np.concatenate((f, archive['f']), axis=0)
archive['g'] = np.concatenate((g, archive['g']), axis=0)
cv = np.copy(archive['g'])
index = np.any(archive['g'] > 0, axis=1)
cv[archive['g'] <= 0] = 0
cv = np.sum(cv, axis=1)
acv = np.sum(archive['g'], axis=1)
acv[index] = np.copy(cv[index])
archive['feasible_index'] = cv <= 0
archive['feasible_index'] = np.vstack(
np.asarray(archive['feasible_index']).flatten())
archive['cv'] = np.vstack(np.asarray(cv).flatten())
archive['acv'] = np.vstack(np.asarray(acv).flatten())
feasible = archive['f'][archive['feasible_index'][:, 0], :]
if feasible.size > 0:
nd = NonDominatedSorting()
index = nd.do(F=feasible, only_non_dominated_front=True)
archive['non_dominated_front'] = archive['x'][index]
else:
archive['non_dominated_front'] = np.empty([0, f.size])
self.n_eval = archive["x"].shape[0]
return archive
def test_rank_and_crowding_distance(self):
for i, D in enumerate(self.data):
survivor_and_last_front = np.where(D['rank'] != -1.0)[0]
crowding = D['crowding'][survivor_and_last_front]
rank = D['rank'][survivor_and_last_front].astype(np.int)
F = D['F'][survivor_and_last_front, :]
fronts, _rank = NonDominatedSorting().do(F, return_rank=True)
_rank += 1
_crowding = np.full(len(F), np.nan)
for front in fronts:
_crowding[front] = calc_crowding_distance(F[front])
is_equal = np.all(rank == _rank)
if not is_equal:
index = np.where(rank == _rank)
print(index)
print(D['rank'][index])
print(D['F'][index])
self.assertTrue(is_equal)
is_equal = np.all(np.abs(_crowding - crowding) < 0.001)
if not is_equal:
index = np.where(np.abs(_crowding - crowding) > 0.001)[0]
index = index[np.argsort(rank[index])]
# only an error if it is not a duplicate F value
for i_not_equal in index:
if len(
np.where(np.all(F[i_not_equal, :] == F,
axis=1))[0]) == 1:
print("-" * 30)
print("Generation: ", i)
print("Is rank equal: ", np.all(rank == _rank))
print(index)
print(rank[index])
print(F[index])
print(
np.concatenate(
[_crowding[:, None], crowding[:, None]],
axis=1)[index, :])
print()
self.assertTrue(is_equal)
def calc_normalized_constraints(self, G):
# update the ideal point for constraints
if self.min_constraints is None:
self.min_constraints = np.full(G.shape[1], np.inf)
self.min_constraints = np.min(np.vstack((self.min_constraints, G)), axis=0)
# update the nadir point for constraints
non_dominated = NonDominatedSorting().do(G, return_rank=True, only_non_dominated_front=True)
if self.max_constraints is None:
self.max_constraints = np.full(G.shape[1], np.inf)
self.max_constraints = np.min(np.vstack((self.max_constraints, np.max(G[non_dominated, :], axis=0))), axis=0)
return normalize(G, self.min_constraints, self.max_constraints)
def _calc(self, F):
non_dom = NonDominatedSorting().do(F, only_non_dominated_front=True)
_F = F[non_dom, :]
if self.normalize:
hv = _HyperVolume(np.ones(F.shape[1]))
_F = normalize(_F,
x_min=np.min(self.pf, axis=0),
x_max=np.max(self.pf, axis=0))
else:
hv = _HyperVolume(np.max(self.pf, axis=0))
val = hv.compute(_F)
return val
def _calc(self, F):
# only consider the non-dominated solutions for HV
non_dom = NonDominatedSorting().do(F, only_non_dominated_front=True)
_F = np.copy(F[non_dom, :])
if self.normalize:
# because we normalize now the reference point is (1,...1)
ref_point = np.ones(F.shape[1])
hv = _HyperVolume(ref_point)
_F = normalize(_F, x_min=self.ideal_point, x_max=self.nadir_point)
else:
hv = _HyperVolume(self.ref_point)
val = hv.compute(_F)
return val
def solve(fd: FoodDistribution):
problem = SolverProblem(fd)
method = nsga2(pop_size=70)
t = time.time()
print('start')
res = minimize(problem,
method,
termination=('n_gen', 20),
seed=2,
save_history=True,
disp=True)
print('end: ', time.time() - t)
plt.figure(1)
plt.clf()
for g, a in enumerate(res.history):
a.opt = a.pop.copy()
a.opt = a.opt[a.opt.collect(lambda ind: ind.feasible)[:, 0]]
I = NonDominatedSorting().do(a.opt.get("F"),
only_non_dominated_front=True)
a.opt = a.opt[I]
X, F, CV, G = a.opt.get("X", "F", "CV", "G")
plt.figure(1)
plt.scatter(F[:, 0], F[:, 1], c=[[g / len(res.history), 0, 0]], s=5**2)
plt.figure(2)
plt.clf()
plt.scatter(F[:, 0], F[:, 1], s=5**2)
plt.xlabel('remaining demand')
plt.ylabel('cost')
plt.savefig('../g_{}.eps'.format(g), format='eps')
plt.figure(1)
#plotting.plot(res.F, no_fill=True, show=False)
plt.xlabel('remaining demand')
plt.ylabel('cost')
plt.show()
plt.savefig('../scatter.eps', format='eps')
return res.X
def _do(self, pop, n_survive, D=None, **kwargs):
# attributes to be set after the survival
F = pop.get("F")
# find or usually update the new ideal point - from feasible solutions
self.ideal_point = np.min(np.vstack((self.ideal_point, F)), axis=0)
self.worst_point = np.max(np.vstack((self.worst_point, F)), axis=0)
# calculate the fronts of the population
fronts, rank = NonDominatedSorting().do(F,
return_rank=True,
n_stop_if_ranked=n_survive)
non_dominated, last_front = fronts[0], fronts[-1]
# find the extreme points for normalization
self.extreme_points = get_extreme_points_c(
F[non_dominated, :],
self.ideal_point,
extreme_points=self.extreme_points)
# find the intercepts for normalization and do backup if gaussian elimination fails
worst_of_population = np.max(F, axis=0)
worst_of_front = np.max(F[non_dominated, :], axis=0)
self.nadir_point = get_nadir_point(self.extreme_points,
self.ideal_point, self.worst_point,
worst_of_population, worst_of_front)
# consider only the population until we come to the splitting front
I = np.concatenate(fronts)
pop, rank, F = pop[I], rank[I], F[I]
# update the front indices for the current population
counter = 0
for i in range(len(fronts)):
for j in range(len(fronts[i])):
fronts[i][j] = counter
counter += 1
# normalize the whole population by the estimations made
N = normalize(F, self.ideal_point, self.nadir_point)
# the final indices of surviving individuals
survivors = []
for k, front in enumerate(fronts):
# calculate the crowding distance of the front
crowding_of_front = calc_asf_crowding_distance(N[front, :])
# save rank and crowding in the individual class
for j, i in enumerate(front):
pop[i].set("rank", k)
pop[i].set("crowding", crowding_of_front[j])
# current front sorted by crowding distance if splitting
if len(survivors) + len(front) > n_survive:
I = randomized_argsort(crowding_of_front,
order='descending',
method='numpy')
I = I[:(n_survive - len(survivors))]
# otherwise take the whole front unsorted
else:
I = np.arange(len(front))
# extend the survivors by all or selected individuals
survivors.extend(front[I])
return pop[survivors]
def test_run(self):
ref_dirs = np.array(self.data['ref_dir'])
survival = ReferenceLineSurvival(ref_dirs)
D = self.data['hist'][0]
pop = Population()
pop.X = np.array(D['before_X'])
pop.F = np.array(D['before_F'])
_, _rank = NonDominatedSorting(epsilon=1e-10).do(pop.F,
return_rank=True)
rank = np.array(D['before_rank'])
if not np.all(_rank + 1 == rank):
print("")
self.assertTrue(np.all(_rank + 1 == rank))
survival.do(pop, pop.size())
for i, D in enumerate(self.data['hist']):
out = {}
vars = {'out': out}
pop = Population()
pop.X = np.array(D['before_X'])
pop.F = np.array(D['before_F'])
off = Population()
off.X = np.array(D['off_X'])
off.F = np.array(D['off_F'])
pop.merge(off)
cand = Population()
cand.X = np.array(D['cand_X'])
cand.F = np.array(D['cand_F'])
Configuration.rand.randint = MagicMock()
Configuration.rand.randint.side_effect = D['rnd_niching']
fronts = []
ranks = np.array(D['cand_rank'])
for r in np.unique(ranks):
fronts.append(np.where(ranks == r)[0].tolist())
NonDominatedSorting.do = MagicMock()
NonDominatedSorting.do.return_value = [
np.array(front) for front in fronts
], ranks - 1
cand_copy = cand.copy()
# necessary because only candidates are provided
if survival.ideal_point is None:
survival.ideal_point = np.min(pop.F, axis=0)
else:
survival.ideal_point = np.min(np.concatenate(
[survival.ideal_point[None, :], pop.F], axis=0),
axis=0)
survival.do(cand, pop.size() / 2, **vars)
is_equal = np.all(
survival.extreme_points == np.array(D['extreme']))
self.assertTrue(is_equal)
is_equal = np.all(survival.ideal_point == np.array(D['ideal']))
self.assertTrue(is_equal)
is_equal = np.all(
np.abs(survival.intercepts -
np.array(D['intercepts'])) < 0.0001)
if not is_equal:
print(i)
print(survival.intercepts, np.array(D['intercepts']))
self.assertTrue(is_equal)
niche_of_individuals, dist_to_niche = associate_to_niches(
cand_copy.F, ref_dirs, survival.ideal_point,
survival.intercepts)
for r, v in enumerate(D['ref_dir']):
self.assertTrue(np.all(ref_dirs[niche_of_individuals[r]] == v))
is_equal = np.all(
np.abs(dist_to_niche - np.array(D['perp_dist'])) < 0.000001)
if not is_equal:
print(i)
self.assertTrue(is_equal)
surv_pop = Population()
surv_pop.X = np.array(D['X'])
surv_pop.F = np.array(D['F'])
for k in range(surv_pop.size()):
is_equal = np.any(np.all(surv_pop.X[k, :] == cand.X, axis=1))
if not is_equal:
print(i)
print(k)
self.assertTrue(is_equal)
for k in range(cand.size()):
is_equal = np.any(np.all(cand.F[k, :] == surv_pop.F, axis=1))
self.assertTrue(is_equal)
def solve(self,
problem,
termination,
seed=None,
disp=False,
callback=None,
save_history=False,
pf=None,
**kwargs):
"""
Solve a given problem by a given evaluator. The evaluator determines the termination condition and
can either have a maximum budget, hypervolume or whatever. The problem can be any problem the algorithm
is able to solve.
Parameters
----------
problem: class
Problem to be solved by the algorithm
termination: class
object that evaluates and saves the number of evaluations and determines the stopping condition
seed: int
Random seed for this run. Before the algorithm starts this seed is set.
disp : bool
If it is true than information during the algorithm execution are displayed
callback : func
A callback function can be passed that is executed every generation. The parameters for the function
are the algorithm itself, the number of evaluations so far and the current population.
def callback(algorithm):
pass
save_history : bool
If true, a current snapshot of each generation is saved.
pf : np.array
The Pareto-front for the given problem. If provided performance metrics are printed during execution.
Returns
-------
res : dict
A dictionary that saves all the results of the algorithm. Also, the history if save_history is true.
"""
# set the random seed for generator
if seed is not None:
random.seed(seed)
# the evaluator object which is counting the evaluations
self.evaluator = Evaluator()
self.problem = problem
self.termination = termination
self.pf = pf
self.disp = disp
self.callback = callback
self.save_history = save_history
# call the algorithm to solve the problem
pop = self._solve(problem, termination)
# get the optimal result by filtering feasible and non-dominated
opt = pop.copy()
opt = opt[opt.collect(lambda ind: ind.feasible)[:, 0]]
# if at least one feasible solution was found
if len(opt) > 0:
if problem.n_obj > 1:
I = NonDominatedSorting().do(opt.get("F"),
only_non_dominated_front=True)
opt = opt[I]
X, F, CV, G = opt.get("X", "F", "CV", "G")
else:
opt = opt[np.argmin(opt.get("F"))]
X, F, CV, G = opt.X, opt.F, opt.CV, opt.G
else:
opt = None
res = Result(opt, opt is None, "")
res.algorithm, res.problem, res.pf = self, problem, pf
res.pop = pop
if opt is not None:
res.X, res.F, res.CV, res.G = X, F, CV, G
res.history = self.history
return res
def _filter_fast(self):
filtered_pop = NonDominatedSorting.get_non_dominated(
self.whole_pop, self.curr_pop)
return filtered_pop
def seeking(P, gamma=210):
P_F = P.get('F')
idx_front_0 = NonDominatedSorting().do(P_F,
n_stop_if_ranked=len(P),
only_non_dominated_front=True)
PS = P[idx_front_0].copy()
PF = P_F[idx_front_0].copy()
# Normalize validation error for calculating angle between two individuals
PF_norm = PF.copy()
mi_f0 = np.min(PF[:, 0])
ma_f0 = np.max(PF[:, 0])
mi_f1 = np.min(PF[:, 1])
ma_f1 = np.max(PF[:, 1])
PF_norm[:, 0] = (PF[:, 0] - mi_f0) / (ma_f0 - mi_f0)
PF_norm[:, 1] = (PF[:, 1] - mi_f1) / (ma_f1 - mi_f1)
new_idx = np.argsort(PF[:, 0])
PS = PS[new_idx]
PF = PF[new_idx]
PF_norm = PF_norm[new_idx]
idx_front_0 = idx_front_0[new_idx]
angle = [np.array([360, 0])]
for i in range(1, len(PF) - 1):
l = None
u = None
for m in range(i - 1, -1, -1):
if np.sum(np.abs(PF[m] - PF[i])) != 0:
l = m
break
for m in range(i + 1, len(PF), 1):
if np.sum(np.abs(PF[m] - PF[i])) != 0:
u = m
break
if l is None or u is None:
angle.append(np.array([0, i]))
else:
position = above_or_below(PF[i], PF[l], PF[u])
if position == -1:
angle.append(
np.array([
calculating_angle(p_middle=PF_norm[i],
p_top=PF_norm[l],
p_bot=PF_norm[u]), i
]))
else:
angle.append(np.array([0, i]))
angle.append(np.array([360, len(PS) - 1]))
angle = np.array(angle)
angle = angle[np.argsort(angle[:, 0])]
angle = angle[angle[:, 0] > gamma]
idx_potential_solutions = np.array(angle[:, 1], dtype=np.int)
return PS, idx_potential_solutions, idx_front_0
def improve_potential_solutions(self, P):
P_F = P.get('F')
front_0 = NonDominatedSorting().do(P_F,
n_stop_if_ranked=len(P),
only_non_dominated_front=True)
PF = P[front_0].copy()
PF_F = P_F[front_0].copy()
# normalize val_error for calculating angle between two individuals
nPF_F = P_F[front_0].copy()
mi_f0 = np.min(PF_F[:, 0])
ma_f0 = np.max(PF_F[:, 0])
mi_f1 = np.min(PF_F[:, 1])
ma_f1 = np.max(PF_F[:, 1])
nPF_F[:, 0] = (PF_F[:, 0] - mi_f0) / (ma_f0 - mi_f0)
nPF_F[:, 1] = (PF_F[:, 1] - mi_f1) / (ma_f1 - mi_f1)
new_idx = np.argsort(PF_F[:, 0]) # --> use for sort
PF = PF[new_idx]
PF_F = PF_F[new_idx]
nPF_F = nPF_F[new_idx]
front_0 = front_0[new_idx]
angle = [np.array([360, 0])]
for i in range(1, len(PF_F) - 1):
l = None
u = None
for m in range(i - 1, -1, -1):
if np.sum(np.abs(PF_F[m] - PF_F[i])) != 0:
l = m
break
for m in range(i + 1, len(PF_F), 1):
if np.sum(np.abs(PF_F[m] - PF_F[i])) != 0:
u = m
break
if l is None or u is None:
angle.append(np.array([0, i]))
else:
tren_hay_duoi = kiem_tra_p1_nam_phia_tren_hay_duoi_p2_p3(
PF_F[i], PF_F[l], PF_F[u])
if tren_hay_duoi == 'duoi':
angle.append(
np.array([
cal_angle(p_middle=nPF_F[i],
p_top=nPF_F[l],
p_bot=nPF_F[u]), i
]))
else:
angle.append(np.array([0, i]))
angle.append(np.array([360, len(PF) - 1]))
angle = np.array(angle)
angle = angle[np.argsort(angle[:, 0])]
angle = angle[angle[:, 0] > 210]
idx_S = np.array(angle[:, 1], dtype=np.int)
S = PF[idx_S].copy()
S = self.local_search_on_X(P, X=S, ls_on_knee_solutions=True)
PF[idx_S] = S
P[front_0] = PF
return P
def _do(self, pop, n_survive, D=None, **kwargs):
# attributes to be set after the survival
F = pop.get("F")
# find or usually update the new ideal point - from feasible solutions
self.ideal_point = np.min(np.vstack(
(self.ideal_point, F, self.ref_points)),
axis=0)
self.worst_point = np.max(np.vstack(
(self.worst_point, F, self.ref_points)),
axis=0)
# calculate the fronts of the population
fronts, rank = NonDominatedSorting().do(F,
return_rank=True,
n_stop_if_ranked=n_survive)
non_dominated, last_front = fronts[0], fronts[-1]
# find the extreme points for normalization
self.extreme_points = get_extreme_points_c(
np.vstack([F[non_dominated], self.ref_points]),
self.ideal_point,
extreme_points=self.extreme_points)
# find the intercepts for normalization and do backup if gaussian elimination fails
worst_of_population = np.max(F, axis=0)
worst_of_front = np.max(F[non_dominated, :], axis=0)
self.nadir_point = get_nadir_point(self.extreme_points,
self.ideal_point, self.worst_point,
worst_of_population, worst_of_front)
# consider only the population until we come to the splitting front
I = np.concatenate(fronts)
pop, rank, F = pop[I], rank[I], F[I]
# update the front indices for the current population
counter = 0
for i in range(len(fronts)):
for j in range(len(fronts[i])):
fronts[i][j] = counter
counter += 1
last_front = fronts[-1]
unit_ref_points = (self.ref_points - self.ideal_point) / (
self.nadir_point - self.ideal_point)
ref_dirs = get_ref_dirs_from_points(unit_ref_points,
self.aspiration_ref_dirs,
mu=self.mu)
self.ref_dirs = denormalize(ref_dirs, self.ideal_point,
self.nadir_point)
# associate individuals to niches
niche_of_individuals, dist_to_niche = associate_to_niches(
F, ref_dirs, self.ideal_point, self.nadir_point)
pop.set('rank', rank, 'niche', niche_of_individuals, 'dist_to_niche',
dist_to_niche)
# if we need to select individuals to survive
if len(pop) > n_survive:
# if there is only one front
if len(fronts) == 1:
n_remaining = n_survive
until_last_front = np.array([], dtype=np.int)
niche_count = np.zeros(len(ref_dirs), dtype=np.int)
# if some individuals already survived
else:
until_last_front = np.concatenate(fronts[:-1])
niche_count = calc_niche_count(
len(ref_dirs), niche_of_individuals[until_last_front])
n_remaining = n_survive - len(until_last_front)
S = niching(pop[last_front], n_remaining, niche_count,
niche_of_individuals[last_front],
dist_to_niche[last_front])
survivors = np.concatenate(
(until_last_front, last_front[S].tolist()))
pop = pop[survivors]
return pop
def _do(self, pop, n_survive, **kwargs):
# get the objective space values and objects
F = pop.get("F")
# the final indices of surviving individuals
survivors = []
# do the non-dominated sorting until splitting front
fronts = NonDominatedSorting().do(F)
if self.normalization == "ever":
# find or usually update the new ideal point - from feasible solutions
self.ideal_point = np.min(np.vstack((self.ideal_point, F)), axis=0)
self.nadir_point = np.max(np.vstack((self.nadir_point, F)), axis=0)
elif self.normalization == "front":
front = fronts[0]
if len(front) > 1:
self.ideal_point = np.min(F[front], axis=0)
self.nadir_point = np.max(F[front], axis=0)
elif self.normalization == "no":
self.ideal_point = np.zeros(self.n_obj)
self.nadir_point = np.ones(self.n_obj)
if self.extreme_points_as_reference_points:
self.ref_points = np.row_stack(
[self.ref_points,
get_extreme_points_c(F, self.ideal_point)])
# calculate the distance matrix from ever solution to all reference point
dist_to_ref_points = calc_norm_pref_distance(F, self.ref_points,
self.weights,
self.ideal_point,
self.nadir_point)
for k, front in enumerate(fronts):
# save rank attributes to the individuals - rank = front here
pop[front].set("rank", np.full(len(front), k))
# number of individuals remaining
n_remaining = n_survive - len(survivors)
# the ranking of each point regarding each reference point (two times argsort is necessary)
rank_by_distance = np.argsort(np.argsort(dist_to_ref_points[front],
axis=0),
axis=0)
# the reference point where the best ranking is coming from
ref_point_of_best_rank = np.argmin(rank_by_distance, axis=1)
# the actual ranking which is used as crowding
ranking = rank_by_distance[np.arange(len(front)),
ref_point_of_best_rank]
if len(front) <= n_remaining:
# we can simply copy the crowding to ranking. not epsilon selection here
crowding = ranking
I = np.arange(len(front))
else:
# Distance from solution to every other solution and set distance to itself to infinity
dist_to_others = calc_norm_pref_distance(
F[front], F[front], self.weights, self.ideal_point,
self.nadir_point)
np.fill_diagonal(dist_to_others, np.inf)
# the crowding that will be used for selection
crowding = np.full(len(front), np.nan)
# solutions which are not already selected - for
not_selected = np.argsort(ranking)
# until we have saved a crowding for each solution
while len(not_selected) > 0:
# select the closest solution
idx = not_selected[0]
# set crowding for that individual
crowding[idx] = ranking[idx]
# need to remove myself from not-selected array
to_remove = [idx]
# Group of close solutions
dist = dist_to_others[idx][not_selected]
group = not_selected[np.where(dist < self.epsilon)[0]]
# if there exists solution with a distance less than epsilon
if len(group):
# discourage them by giving them a high crowding
crowding[group] = ranking[group] + np.round(
len(front) / 2)
# remove group from not_selected array
to_remove.extend(group)
not_selected = np.array(
[i for i in not_selected if i not in to_remove])
# now sort by the crowding (actually modified rank) ascending and let the best survive
I = np.argsort(crowding)[:n_remaining]
# set the crowding to all individuals
pop[front].set("crowding", crowding)
# extend the survivors by all or selected individuals
survivors.extend(front[I])
# inverse of crowding because nsga2 does maximize it (then tournament selection can stay the same)
pop.set("crowding", -pop.get("crowding"))
return pop[survivors]
def _do(self, pop, n_survive, algorithm=None, **kwargs):
if True:
if self.archive is None:
self.archive = pop
else:
self.archive = self.archive.merge(pop)
# get the function values of the current archive for operations
F = self.archive.get("F")
# filter out all the duplicate solutions
I = np.logical_not(default_is_duplicate(F))
self.archive, F = self.archive[I], F[I]
# get only the non-dominated solutions
I = NonDominatedSorting().do(F, only_non_dominated_front=True)
self.archive, F = self.archive[I], F[I]
if len(self.archive) > self.n_archive:
cd = calc_crowding_distance(F)
self.archive = self.archive[np.argsort(cd)[::-1]
[:self.n_archive]]
# attributes to be set after the survival
pop.merge(self.archive)
F = pop.get("F")
# find or usually update the new ideal point - from feasible solutions
self.ideal_point = np.min(np.vstack((self.ideal_point, F)), axis=0)
self.worst_point = np.max(np.vstack((self.worst_point, F)), axis=0)
# calculate the fronts of the population
fronts, rank = NonDominatedSorting(epsilon=1e-10).do(
F, return_rank=True, n_stop_if_ranked=n_survive)
non_dominated, last_front = fronts[0], fronts[-1]
# find the extreme points for normalization
self.extreme_points = non_dominated[get_extreme_points(
F[non_dominated, :], self.ideal_point)]
# find the intercepts for normalization and do backup if gaussian elimination fails
worst_of_population = np.max(F, axis=0)
worst_of_front = np.max(F[non_dominated, :], axis=0)
self.nadir_point = get_nadir_point(F[self.extreme_points],
self.ideal_point, self.worst_point,
worst_of_population, worst_of_front)
# associate individuals to niches
pop.set('rank', rank)
# if we need to select individuals to survive
if len(pop) > n_survive:
for i in range(len(fronts)):
fronts[i] = np.array(
[j for j in fronts[i] if j not in self.extreme_points])
survivors = np.unique(self.extreme_points).tolist()
for k, front in enumerate(fronts):
# current front sorted by crowding distance if splitting
if len(survivors) + len(front) > n_survive:
I = selection(survivors, list(front), F,
(n_survive - len(survivors)))
survivors.extend(I)
# otherwise take the whole front unsorted
else:
# extend the survivors by all or selected individuals
survivors.extend(front)
pop = pop[survivors]
return pop
def _seeking(self, pop, **kwargs):
pop_F = pop.get('F')
pos_front_0 = NonDominatedSorting().do(pop_F,
n_stop_if_ranked=len(pop),
only_non_dominated_front=True)
pareto_set = pop[pos_front_0].copy()
pf = pop_F[pos_front_0].copy()
# Normalize validation error for calculating angle between two individuals
pf_norm = pf.copy()
mi_f0 = np.min(pf[:, 0])
ma_f0 = np.max(pf[:, 0])
mi_f1 = np.min(pf[:, 1])
ma_f1 = np.max(pf[:, 1])
pf_norm[:, 0] = (pf[:, 0] - mi_f0) / (ma_f0 - mi_f0)
pf_norm[:, 1] = (pf[:, 1] - mi_f1) / (ma_f1 - mi_f1)
new_idx = np.argsort(pf[:, 0])
pareto_set = pareto_set[new_idx]
pf = pf[new_idx]
pf_norm = pf_norm[new_idx]
pos_front_0 = pos_front_0[new_idx]
angle = [np.array([360, 0])]
for i in range(1, len(pf) - 1):
l = None
u = None
for m in range(i - 1, -1, -1):
if np.sum(np.abs(pf[m] - pf[i])) != 0:
l = m
break
for m in range(i + 1, len(pf), 1):
if np.sum(np.abs(pf[m] - pf[i])) != 0:
u = m
break
if l is None or u is None:
angle.append(np.array([0, i]))
else:
position = above_or_below(pf[i], pf[l], pf[u])
if position == -1:
angle.append(
np.array([
cal_angle(p_middle=pf_norm[i],
p_top=pf_norm[l],
p_bot=pf_norm[u]), i
]))
else:
angle.append(np.array([0, i]))
angle.append(np.array([360, len(pareto_set) - 1]))
angle = np.array(angle)
angle = angle[np.argsort(angle[:, 0])]
angle = angle[angle[:, 0] > self.gamma]
pos_potential_sols = np.array(angle[:, 1], dtype=np.int)
return pareto_set, pos_potential_sols, pos_front_0