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# Author: Simon Blanke |
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# Email: [email protected] |
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# License: MIT License |
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import random |
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import numpy as np |
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from . import HillClimbingOptimizer |
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from ...base_positioner import BasePositioner |
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from scipy.spatial.distance import euclidean |
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def gaussian(distance, sig): |
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return sig * np.exp(-np.power(distance, 2.0) / (2 * np.power(sig, 2.0))) |
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class TabuOptimizer(HillClimbingOptimizer): |
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def __init__(self, *args, **kwargs): |
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super().__init__(*args, **kwargs) |
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def _tabu_pos(self, pos, _p_): |
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_p_.add_tabu(pos) |
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return _p_ |
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def _iterate(self, i, _cand_, _p_, X, y): |
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_p_.pos_new = _p_.move_climb(_cand_, _p_.pos_current) |
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_p_.score_new = _cand_.eval_pos(_p_.pos_new, X, y) |
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if _p_.score_new > _cand_.score_best: |
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_cand_, _p_ = self._update_pos(_cand_, _p_) |
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else: |
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_p_ = self._tabu_pos(_p_.pos_new, _p_) |
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return _cand_ |
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def _init_opt_positioner(self, _cand_, X, y): |
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return super()._init_base_positioner( |
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_cand_, positioner=TabuPositioner, pos_para=self.pos_para |
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) |
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class TabuPositioner(BasePositioner): |
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def __init__(self, epsilon): |
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super().__init__(epsilon) |
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self.tabus = [] |
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def add_tabu(self, tabu): |
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self.tabus.append(tabu) |
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def move_climb(self, _cand_, pos, epsilon_mod=1): |
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sigma = 3 + _cand_._space_.dim * self.epsilon * epsilon_mod |
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pos_normal = np.random.normal(pos, sigma, pos.shape) |
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pos_new_int = np.rint(pos_normal) |
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for tabu in self.tabus: |
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distance = euclidean(pos_new_int, tabu) |
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sigma_mean = sigma.mean() |
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p_discard = gaussian(distance, sigma_mean) |
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rand = random.uniform(0, 1) |
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if p_discard > rand: |
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pos_normal = np.random.normal(pos, sigma, pos.shape) |
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pos_new_int = np.rint(pos_normal) |
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n_zeros = [0] * len(_cand_._space_.dim) |
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pos = np.clip(pos_new_int, n_zeros, _cand_._space_.dim) |
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return pos |
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