'TPESampler' 对象没有属性“_group”
'TPESampler' object has no attribute '_group'
今天在 Optuna 2.8.0 的 Colab 上加载 后尝试优化它时，我的研究中出现了以下错误。每次试验开始或结束时，我都会用 joblib 保存一项研究，每个试验都保存在一个单独的文件中。我以前从来没有遇到过这个问题，也不确定到底是什么原因造成的。
Colab 显示以下跟踪：
/usr/local/lib/python3.7/dist-packages/optuna/study.py in optimize(self, func, n_trials, timeout, n_jobs, catch, callbacks, gc_after_trial, show_progress_bar)
408 callbacks=callbacks,
409 gc_after_trial=gc_after_trial,
--> 410 show_progress_bar=show_progress_bar,
411 )
412
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _optimize(study, func, n_trials, timeout, n_jobs, catch, callbacks, gc_after_trial, show_progress_bar)
73 reseed_sampler_rng=False,
74 time_start=None,
---> 75 progress_bar=progress_bar,
76 )
77 else:
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _optimize_sequential(study, func, n_trials, timeout, catch, callbacks, gc_after_trial, reseed_sampler_rng, time_start, progress_bar)
160
161 try:
--> 162 trial = _run_trial(study, func, catch)
163 except Exception:
164 raise
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _run_trial(study, func, catch)
195 failed_trial_callback(study, failed_trial)
196
--> 197 trial = study.ask()
198
199 state: Optional[TrialState] = None
/usr/local/lib/python3.7/dist-packages/optuna/study.py in ask(self, fixed_distributions)
485 if trial_id is None:
486 trial_id = self._storage.create_new_trial(self._study_id)
--> 487 trial = trial_module.Trial(self, trial_id)
488
489 for name, param in fixed_distributions.items():
/usr/local/lib/python3.7/dist-packages/optuna/trial/_trial.py in __init__(self, study, trial_id)
55 self.storage = self.study._storage
56
---> 57 self._init_relative_params()
58
59 def _init_relative_params(self) -> None:
/usr/local/lib/python3.7/dist-packages/optuna/trial/_trial.py in _init_relative_params(self)
65 self.relative_search_space = self.study.sampler.infer_relative_search_space(study, trial)
66 self.relative_params = self.study.sampler.sample_relative(
---> 67 study, trial, self.relative_search_space
68 )
69
/usr/local/lib/python3.7/dist-packages/optuna/samplers/_tpe/sampler.py in sample_relative(self, study, trial, search_space)
327 self._raise_error_if_multi_objective(study)
328
--> 329 if self._group:
330 assert self._search_space_group is not None
331 params = {}
AttributeError: 'TPESampler' object has no attribute '_group'
PS。有趣的是，这项研究的问题似乎并不存在于我的本地机器上。我使用的是 2.5.0.
版本
刚从Optuna开发者那里得到答案：
A (private) attribute was introduced to the TPESampler in v2.8 and if
you've pickled or serialized the sampler before this introduction,
you'll encounter this AttributeError when unpickling it with v2.8.
这个问题的解决方案是重新实例化采样器对象并将其替换为 study.sampler:
study = optuna.load_study(...)
sampler = optuna.samplers.TPESampler()
study.sampler = sampler
study.optimize(...)
PS。修枝剪可能会出现同样的问题。如果是这样，也重新实例化修剪器！
今天在 Optuna 2.8.0 的 Colab 上加载 后尝试优化它时，我的研究中出现了以下错误。每次试验开始或结束时，我都会用 joblib 保存一项研究，每个试验都保存在一个单独的文件中。我以前从来没有遇到过这个问题，也不确定到底是什么原因造成的。
Colab 显示以下跟踪：
/usr/local/lib/python3.7/dist-packages/optuna/study.py in optimize(self, func, n_trials, timeout, n_jobs, catch, callbacks, gc_after_trial, show_progress_bar)
408 callbacks=callbacks,
409 gc_after_trial=gc_after_trial,
--> 410 show_progress_bar=show_progress_bar,
411 )
412
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _optimize(study, func, n_trials, timeout, n_jobs, catch, callbacks, gc_after_trial, show_progress_bar)
73 reseed_sampler_rng=False,
74 time_start=None,
---> 75 progress_bar=progress_bar,
76 )
77 else:
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _optimize_sequential(study, func, n_trials, timeout, catch, callbacks, gc_after_trial, reseed_sampler_rng, time_start, progress_bar)
160
161 try:
--> 162 trial = _run_trial(study, func, catch)
163 except Exception:
164 raise
/usr/local/lib/python3.7/dist-packages/optuna/_optimize.py in _run_trial(study, func, catch)
195 failed_trial_callback(study, failed_trial)
196
--> 197 trial = study.ask()
198
199 state: Optional[TrialState] = None
/usr/local/lib/python3.7/dist-packages/optuna/study.py in ask(self, fixed_distributions)
485 if trial_id is None:
486 trial_id = self._storage.create_new_trial(self._study_id)
--> 487 trial = trial_module.Trial(self, trial_id)
488
489 for name, param in fixed_distributions.items():
/usr/local/lib/python3.7/dist-packages/optuna/trial/_trial.py in __init__(self, study, trial_id)
55 self.storage = self.study._storage
56
---> 57 self._init_relative_params()
58
59 def _init_relative_params(self) -> None:
/usr/local/lib/python3.7/dist-packages/optuna/trial/_trial.py in _init_relative_params(self)
65 self.relative_search_space = self.study.sampler.infer_relative_search_space(study, trial)
66 self.relative_params = self.study.sampler.sample_relative(
---> 67 study, trial, self.relative_search_space
68 )
69
/usr/local/lib/python3.7/dist-packages/optuna/samplers/_tpe/sampler.py in sample_relative(self, study, trial, search_space)
327 self._raise_error_if_multi_objective(study)
328
--> 329 if self._group:
330 assert self._search_space_group is not None
331 params = {}
AttributeError: 'TPESampler' object has no attribute '_group'
PS。有趣的是，这项研究的问题似乎并不存在于我的本地机器上。我使用的是 2.5.0.
版本刚从Optuna开发者那里得到答案：
A (private) attribute was introduced to the TPESampler in v2.8 and if you've pickled or serialized the sampler before this introduction, you'll encounter this AttributeError when unpickling it with v2.8.
这个问题的解决方案是重新实例化采样器对象并将其替换为 study.sampler:
study = optuna.load_study(...)
sampler = optuna.samplers.TPESampler()
study.sampler = sampler
study.optimize(...)
PS。修枝剪可能会出现同样的问题。如果是这样，也重新实例化修剪器！