callback_lambda | R Documentation |
This callback is constructed with anonymous functions that will be called
at the appropriate time (during Model.{fit | evaluate | predict}
).
Note that the callbacks expects positional arguments, as:
on_epoch_begin
and on_epoch_end
expect two positional arguments:
epoch
, logs
on_train_begin
and on_train_end
expect one positional argument:
logs
on_train_batch_begin
and on_train_batch_end
expect two positional
arguments: batch
, logs
See Callback
class definition for the full list of functions and their
expected arguments.
callback_lambda(
on_epoch_begin = NULL,
on_epoch_end = NULL,
on_train_begin = NULL,
on_train_end = NULL,
on_train_batch_begin = NULL,
on_train_batch_end = NULL,
...
)
on_epoch_begin |
called at the beginning of every epoch. |
on_epoch_end |
called at the end of every epoch. |
on_train_begin |
called at the beginning of model training. |
on_train_end |
called at the end of model training. |
on_train_batch_begin |
called at the beginning of every train batch. |
on_train_batch_end |
called at the end of every train batch. |
... |
Any function in |
A Callback
instance that can be passed to fit.keras.src.models.model.Model()
.
# Print the batch number at the beginning of every batch. batch_print_callback <- callback_lambda( on_train_batch_begin = function(batch, logs) { print(batch) } ) # Stream the epoch loss to a file in new-line delimited JSON format # (one valid JSON object per line) json_log <- file('loss_log.json', open = 'wt') json_logging_callback <- callback_lambda( on_epoch_end = function(epoch, logs) { jsonlite::write_json( list(epoch = epoch, loss = logs$loss), json_log, append = TRUE ) }, on_train_end = function(logs) { close(json_log) } ) # Terminate some processes after having finished model training. processes <- ... cleanup_callback <- callback_lambda( on_train_end = function(logs) { for (p in processes) { if (is_alive(p)) { terminate(p) } } } ) model %>% fit( ..., callbacks = list( batch_print_callback, json_logging_callback, cleanup_callback ) )
Other callbacks:
Callback()
callback_backup_and_restore()
callback_csv_logger()
callback_early_stopping()
callback_learning_rate_scheduler()
callback_model_checkpoint()
callback_reduce_lr_on_plateau()
callback_remote_monitor()
callback_swap_ema_weights()
callback_tensorboard()
callback_terminate_on_nan()
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