tf.keras.callbacks.Callback

Abstract base class used to build new callbacks.

Used in the notebooks

Used in the guide Used in the tutorials

The logs dictionary that callback methods take as argument will contain keys for quantities relevant to the current batch or epoch (see method-specific docstrings).

params Dict. Training parameters (eg. verbosity, batch size, number of epochs...).
model Instance of keras.models.Model. Reference of the model being trained.

Methods

on_batch_begin

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A backwards compatibility alias for on_train_batch_begin.

on_batch_end

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A backwards compatibility alias for on_train_batch_end.

on_epoch_begin

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Called at the start of an epoch.

Subclasses should override for any actions to run. This function should only be called during TRAIN mode.

Arguments
epoch Integer, index of epoch.
logs Dict. Currently no data is passed to this argument for this method but that may change in the future.

on_epoch_end

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Called at the end of an epoch.

Subclasses should override for any actions to run. This function should only be called during TRAIN mode.

Arguments
epoch Integer, index of epoch.
logs Dict, metric results for this training epoch, and for the validation epoch if validation is performed. Validation result keys are prefixed with val_.

on_predict_batch_begin

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Called at the beginning of a batch in predict methods.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict, contains the return value of model.predict_step, it typically returns a dict with a key 'outputs' containing the model's outputs.

on_predict_batch_end

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Called at the end of a batch in predict methods.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict. Aggregated metric results up until this batch.

on_predict_begin

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Called at the beginning of prediction.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently no data is passed to this argument for this method but that may change in the future.

on_predict_end

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Called at the end of prediction.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently no data is passed to this argument for this method but that may change in the future.

on_test_batch_begin

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Called at the beginning of a batch in evaluate methods.

Also called at the beginning of a validation batch in the fit methods, if validation data is provided.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict, contains the return value of model.test_step. Typically, the values of the Model's metrics are returned. Example: {'loss': 0.2, 'accuracy': 0.7}.

on_test_batch_end

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Called at the end of a batch in evaluate methods.

Also called at the end of a validation batch in the fit methods, if validation data is provided.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict. Aggregated metric results up until this batch.

on_test_begin

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Called at the beginning of evaluation or validation.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently no data is passed to this argument for this method but that may change in the future.

on_test_end

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Called at the end of evaluation or validation.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently the output of the last call to on_test_batch_end() is passed to this argument for this method but that may change in the future.

on_train_batch_begin

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Called at the beginning of a training batch in fit methods.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict, contains the return value of model.train_step. Typically, the values of the Model's metrics are returned. Example: {'loss': 0.2, 'accuracy': 0.7}.

on_train_batch_end

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Called at the end of a training batch in fit methods.

Subclasses should override for any actions to run.

Arguments
batch Integer, index of batch within the current epoch.
logs Dict. Aggregated metric results up until this batch.

on_train_begin

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Called at the beginning of training.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently no data is passed to this argument for this method but that may change in the future.

on_train_end

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Called at the end of training.

Subclasses should override for any actions to run.

Arguments
logs Dict. Currently the output of the last call to on_epoch_end() is passed to this argument for this method but that may change in the future.

set_model

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set_params

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