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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 .simulated_annealing import SimulatedAnnealingOptimizer |
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from ..local import HillClimbingPositioner |
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class ParallelTemperingOptimizer(SimulatedAnnealingOptimizer): |
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def __init__(self, _main_args_, _opt_args_): |
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super().__init__(_main_args_, _opt_args_) |
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self.n_iter_swap = int(self._main_args_.n_iter / self._opt_args_.n_swaps) |
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def _init_annealers(self, _cand_): |
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_p_list_ = [ |
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System(**self._opt_args_.kwargs_opt, temp=temp) |
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for temp in self._opt_args_.system_temperatures |
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] |
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for _p_ in _p_list_: |
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_p_.pos_current = _cand_._space_.get_random_pos() |
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_p_.pos_best = _p_.pos_current |
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return _p_list_ |
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def _swap_pos(self, _cand_, _p_list_): |
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_p_list_temp = _p_list_[:] |
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for _p1_ in _p_list_: |
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rand = random.uniform(0, 1) |
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_p2_ = np.random.choice(_p_list_temp) |
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p_accept = self._accept_swap(_p1_, _p2_) |
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if p_accept > rand: |
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temp_temp = _p1_.temp # haha! |
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_p1_.temp = _p2_.temp |
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_p2_.temp = temp_temp |
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def _accept_swap(self, _p1_, _p2_): |
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denom = _p1_.score_current + _p2_.score_current |
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if denom == 0: |
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return 100 |
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elif abs(denom) == np.inf: |
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return 0 |
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else: |
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score_diff_norm = (_p1_.score_current - _p2_.score_current) / denom |
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temp = (1 / _p1_.temp) - (1 / _p2_.temp) |
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return np.exp(score_diff_norm * temp) |
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def _anneal_system(self, _cand_, _p_): |
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_cand_ = super()._iterate(0, _cand_, _p_) |
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return _cand_ |
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def _iterate(self, i, _cand_, _p_list_): |
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_p_current = _p_list_[i % len(_p_list_)] |
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_cand_ = self._anneal_system(_cand_, _p_current) |
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if self.n_iter_swap != 0 and i % self.n_iter_swap == 0: |
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self._swap_pos(_cand_, _p_list_) |
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return _cand_ |
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def _init_opt_positioner(self, _cand_): |
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_p_list_ = self._init_annealers(_cand_) |
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return _p_list_ |
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class System(HillClimbingPositioner): |
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def __init__(self, *args, **kwargs): |
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super().__init__(*args, **kwargs) |
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self.temp = kwargs["temp"] |
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