This callback is constructed with anonymous functions that will be called at the appropriate time. Note that the callbacks expects positional arguments, as:

callback_lambda(
on_epoch_begin = NULL,
on_epoch_end = NULL,
on_batch_begin = NULL,
on_batch_end = NULL,
on_train_batch_begin = NULL,
on_train_batch_end = NULL,
on_train_begin = NULL,
on_train_end = NULL,
on_predict_batch_begin = NULL,
on_predict_batch_end = NULL,
on_predict_begin = NULL,
on_predict_end = NULL,
on_test_batch_begin = NULL,
on_test_batch_end = NULL,
on_test_begin = NULL,
on_test_end = NULL
)

## Arguments

on_epoch_begin

called at the beginning of every epoch.

on_epoch_end

called at the end of every epoch.

on_batch_begin

called at the beginning of every training batch.

on_batch_end

called at the end of every training batch.

on_train_batch_begin

called at the beginning of every batch.

on_train_batch_end

called at the end of every batch.

on_train_begin

called at the beginning of model training.

on_train_end

called at the end of model training.

on_predict_batch_begin

called at the beginning of a batch in predict methods.

on_predict_batch_end

called at the end of a batch in predict methods.

on_predict_begin

called at the beginning of prediction.

on_predict_end

called at the end of prediction.

on_test_batch_begin

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.

on_test_batch_end

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.

on_test_begin

called at the beginning of evaluation or validation.

on_test_end

called at the end of evaluation or validation.

## Details

• on_epoch_begin and on_epoch_end expect two positional arguments: epoch, logs

• on_batch_*, on_train_batch_*, on_predict_batch_* and on_test_batch_*, expect two positional arguments: batch, logs

• on_train_*, on_test_* and on_predict_* expect one positional argument: logs

Other callbacks: callback_csv_logger(), callback_early_stopping(), callback_learning_rate_scheduler(), callback_model_checkpoint(), callback_progbar_logger(), callback_reduce_lr_on_plateau(), callback_remote_monitor(), callback_tensorboard(), callback_terminate_on_naan()