Source code for optuna.integration.tfkeras

from __future__ import absolute_import

import optuna
from optuna import type_checking

if type_checking.TYPE_CHECKING:
    from typing import Any  # NOQA
    from typing import Dict  # NOQA

try:
    from tensorflow.keras.callbacks import Callback
    _available = True
except ImportError as e:
    _import_error = e
    # TFKerasPruningCallback is disabled because TensorFlow is not available.
    _available = False
    Callback = object


[docs]class TFKerasPruningCallback(Callback): """tf.keras callback to prune unpromising trials. This callback is intend to be compatible for TensorFlow v1 and v2, but only tested with TensorFlow v1. Example: Add a pruning callback which observes validation losses. .. code:: model.fit(x, y, callbacks=[TFKerasPruningCallback(trial, 'val_loss')]) Args: trial: A :class:`~optuna.trial.Trial` corresponding to the current evaluation of the objective function. monitor: An evaluation metric for pruning, e.g., ``val_loss`` or ``val_acc``. """ def __init__(self, trial, monitor): # type: (optuna.trial.Trial, str) -> None super(TFKerasPruningCallback, self).__init__() _check_tensorflow_availability() self.trial = trial self.monitor = monitor def on_epoch_end(self, epoch, logs=None): # type: (int, Dict[str, Any]) -> None logs = logs or {} current_score = logs.get(self.monitor) if current_score is None: return # Report current score and epoch to Optuna's trial. self.trial.report(float(current_score), step=epoch) # Prune trial if needed if self.trial.should_prune(): message = "Trial was pruned at epoch {}.".format(epoch) raise optuna.exceptions.TrialPruned(message)
def _check_tensorflow_availability(): # type: () -> None if not _available: raise ImportError( 'TensorFlow is not available. Please install TensorFlow to use this feature. ' 'TensorFlow can be installed by executing `$ pip install tensorflow`. ' 'For further information, please refer to the installation guide of TensorFlow. ' '(The actual import error is as follows: ' + str(_import_error) + ')')