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Trainer

Customize every aspect of training via flags

Trainer to automate the training.

class pytorch_lightning.trainer.trainer.Trainer(logger=True, checkpoint_callback=True, callbacks=None, default_root_dir=None, gradient_clip_val=0.0, gradient_clip_algorithm='norm', process_position=0, num_nodes=1, num_processes=1, devices=None, gpus=None, auto_select_gpus=False, tpu_cores=None, ipus=None, log_gpu_memory=None, progress_bar_refresh_rate=None, overfit_batches=0.0, track_grad_norm=- 1, check_val_every_n_epoch=1, fast_dev_run=False, accumulate_grad_batches=1, max_epochs=None, min_epochs=None, max_steps=None, min_steps=None, max_time=None, limit_train_batches=1.0, limit_val_batches=1.0, limit_test_batches=1.0, limit_predict_batches=1.0, val_check_interval=1.0, flush_logs_every_n_steps=100, log_every_n_steps=50, accelerator=None, sync_batchnorm=False, precision=32, weights_summary='top', weights_save_path=None, num_sanity_val_steps=2, truncated_bptt_steps=None, resume_from_checkpoint=None, profiler=None, benchmark=False, deterministic=False, reload_dataloaders_every_n_epochs=0, reload_dataloaders_every_epoch=False, auto_lr_find=False, replace_sampler_ddp=True, terminate_on_nan=False, auto_scale_batch_size=False, prepare_data_per_node=True, plugins=None, amp_backend='native', amp_level='O2', distributed_backend=None, move_metrics_to_cpu=False, multiple_trainloader_mode='max_size_cycle', stochastic_weight_avg=False)[source]

Bases: pytorch_lightning.trainer.properties.TrainerProperties, pytorch_lightning.trainer.callback_hook.TrainerCallbackHookMixin, pytorch_lightning.trainer.model_hooks.TrainerModelHooksMixin, pytorch_lightning.trainer.optimizers.TrainerOptimizersMixin, pytorch_lightning.trainer.logging.TrainerLoggingMixin, pytorch_lightning.trainer.training_tricks.TrainerTrainingTricksMixin, pytorch_lightning.trainer.data_loading.TrainerDataLoadingMixin, pytorch_lightning.trainer.deprecated_api.DeprecatedTrainerAttributes

Customize every aspect of training via flags

Parameters

  • accelerator (Union[str, Accelerator, None]) – Previously known as distributed_backend (dp, ddp, ddp2, etc…). Can also take in an accelerator object for custom hardware.

  • accumulate_grad_batches (Union[int, Dict[int, int], List[list]]) – Accumulates grads every k batches or as set up in the dict.

  • amp_backend (str) – The mixed precision backend to use (“native” or “apex”)

  • amp_level (str) – The optimization level to use (O1, O2, etc…).

  • auto_lr_find (Union[bool, str]) – If set to True, will make trainer.tune() run a learning rate finder, trying to optimize initial learning for faster convergence. trainer.tune() method will set the suggested learning rate in self.lr or self.learning_rate in the LightningModule. To use a different key set a string instead of True with the key name.

  • auto_scale_batch_size (Union[str, bool]) – If set to True, will initially run a batch size finder trying to find the largest batch size that fits into memory. The result will be stored in self.batch_size in the LightningModule. Additionally, can be set to either power that estimates the batch size through a power search or binsearch that estimates the batch size through a binary search.

  • auto_select_gpus (bool) – If enabled and gpus is an integer, pick available gpus automatically. This is especially useful when GPUs are configured to be in “exclusive mode”, such that only one process at a time can access them.

  • benchmark (bool) – If true enables cudnn.benchmark.

  • callbacks (Union[List[Callback], Callback, None]) – Add a callback or list of callbacks.

  • checkpoint_callback (bool) – If True, enable checkpointing. It will configure a default ModelCheckpoint callback if there is no user-defined ModelCheckpoint in callbacks.

  • check_val_every_n_epoch (int) – Check val every n train epochs.

  • default_root_dir (Optional[str]) – Default path for logs and weights when no logger/ckpt_callback passed. Default: os.getcwd(). Can be remote file paths such as s3://mybucket/path or ‘hdfs://path/’

  • deterministic (bool) – If true enables cudnn.deterministic.

  • devices (Union[int, str, List[int], None]) – Will be mapped to either gpus, tpu_cores, num_processes or ipus, based on the accelerator type.

  • distributed_backend (Optional[str]) – deprecated. Please use ‘accelerator’

  • fast_dev_run (Union[int, bool]) – runs n if set to n (int) else 1 if set to True batch(es) of train, val and test to find any bugs (ie: a sort of unit test).

  • flush_logs_every_n_steps (int) – How often to flush logs to disk (defaults to every 100 steps).

  • gpus (Union[int, str, List[int], None]) – number of gpus to train on (int) or which GPUs to train on (list or str) applied per node

  • gradient_clip_val (Union[int, float]) – 0 means don’t clip.

  • gradient_clip_algorithm (str) – ‘value’ means clip_by_value, ‘norm’ means clip_by_norm. Default: ‘norm’

  • limit_train_batches (Union[int, float]) – How much of training dataset to check (float = fraction, int = num_batches)

  • limit_val_batches (Union[int, float]) – How much of validation dataset to check (float = fraction, int = num_batches)

  • limit_test_batches (Union[int, float]) – How much of test dataset to check (float = fraction, int = num_batches)

  • limit_predict_batches (Union[int, float]) – How much of prediction dataset to check (float = fraction, int = num_batches)

  • logger (Union[LightningLoggerBase, Iterable[LightningLoggerBase], bool]) – Logger (or iterable collection of loggers) for experiment tracking. A True value uses the default TensorBoardLogger. False will disable logging. If multiple loggers are provided and the save_dir property of that logger is not set, local files (checkpoints, profiler traces, etc.) are saved in default_root_dir rather than in the log_dir of any of the individual loggers.

  • log_gpu_memory (Optional[str]) – None, ‘min_max’, ‘all’. Might slow performance

  • log_every_n_steps (int) – How often to log within steps (defaults to every 50 steps).

  • prepare_data_per_node (bool) – If True, each LOCAL_RANK=0 will call prepare data. Otherwise only NODE_RANK=0, LOCAL_RANK=0 will prepare data

  • process_position (int) – orders the progress bar when running multiple models on same machine.

  • progress_bar_refresh_rate (Optional[int]) – How often to refresh progress bar (in steps). Value 0 disables progress bar. Ignored when a custom progress bar is passed to callbacks. Default: None, means a suitable value will be chosen based on the environment (terminal, Google COLAB, etc.).

  • profiler (Union[BaseProfiler, str, None]) – To profile individual steps during training and assist in identifying bottlenecks.

  • overfit_batches (Union[int, float]) – Overfit a fraction of training data (float) or a set number of batches (int).

  • plugins (Union[List[Union[Plugin, ClusterEnvironment, str]], Plugin, ClusterEnvironment, str, None]) – Plugins allow modification of core behavior like ddp and amp, and enable custom lightning plugins.

  • precision (int) – Double precision (64), full precision (32) or half precision (16). Can be used on CPU, GPU or TPUs.

  • max_epochs (Optional[int]) – Stop training once this number of epochs is reached. Disabled by default (None). If both max_epochs and max_steps are not specified, defaults to max_epochs = 1000.

  • min_epochs (Optional[int]) – Force training for at least these many epochs. Disabled by default (None). If both min_epochs and min_steps are not specified, defaults to min_epochs = 1.

  • max_steps (Optional[int]) – Stop training after this number of steps. Disabled by default (None).

  • min_steps (Optional[int]) – Force training for at least these number of steps. Disabled by default (None).

  • max_time (Union[str, timedelta, Dict[str, int], None]) – Stop training after this amount of time has passed. Disabled by default (None). The time duration can be specified in the format DD:HH:MM:SS (days, hours, minutes seconds), as a datetime.timedelta, or a dictionary with keys that will be passed to datetime.timedelta.

  • num_nodes (int) – number of GPU nodes for distributed training.

  • num_processes (int) – number of processes for distributed training with distributed_backend=”ddp_cpu”

  • num_sanity_val_steps (int) – Sanity check runs n validation batches before starting the training routine. Set it to -1 to run all batches in all validation dataloaders.

  • reload_dataloaders_every_n_epochs (int) – Set to a non-negative integer to reload dataloaders every n epochs. Default: 0

  • reload_dataloaders_every_epoch (bool) –

    Set to True to reload dataloaders every epoch.

    Deprecated since version v1.4: reload_dataloaders_every_epoch has been deprecated in v1.4 and will be removed in v1.6. Please use reload_dataloaders_every_n_epochs.

  • replace_sampler_ddp (bool) – Explicitly enables or disables sampler replacement. If not specified this will toggled automatically when DDP is used. By default it will add shuffle=True for train sampler and shuffle=False for val/test sampler. If you want to customize it, you can set replace_sampler_ddp=False and add your own distributed sampler.

  • resume_from_checkpoint (Union[str, Path, None]) – Path/URL of the checkpoint from which training is resumed. If there is no checkpoint file at the path, start from scratch. If resuming from mid-epoch checkpoint, training will start from the beginning of the next epoch.

  • sync_batchnorm (bool) – Synchronize batch norm layers between process groups/whole world.

  • terminate_on_nan (bool) – If set to True, will terminate training (by raising a ValueError) at the end of each training batch, if any of the parameters or the loss are NaN or +/-inf.

  • tpu_cores (Union[int, str, List[int], None]) – How many TPU cores to train on (1 or 8) / Single TPU to train on [1]

  • ipus (Optional[int]) – How many IPUs to train on.

  • track_grad_norm (Union[int, float, str]) – -1 no tracking. Otherwise tracks that p-norm. May be set to ‘inf’ infinity-norm.

  • truncated_bptt_steps (Optional[int]) – Deprecated in v1.3 to be removed in 1.5. Please use truncated_bptt_steps instead.

  • val_check_interval (Union[int, float]) – How often to check the validation set. Use float to check within a training epoch, use int to check every n steps (batches).

  • weights_summary (Optional[str]) – Prints a summary of the weights when training begins.

  • weights_save_path (Optional[str]) – Where to save weights if specified. Will override default_root_dir for checkpoints only. Use this if for whatever reason you need the checkpoints stored in a different place than the logs written in default_root_dir. Can be remote file paths such as s3://mybucket/path or ‘hdfs://path/’ Defaults to default_root_dir.

  • move_metrics_to_cpu (bool) – Whether to force internal logged metrics to be moved to cpu. This can save some gpu memory, but can make training slower. Use with attention.

  • multiple_trainloader_mode (str) – How to loop over the datasets when there are multiple train loaders. In ‘max_size_cycle’ mode, the trainer ends one epoch when the largest dataset is traversed, and smaller datasets reload when running out of their data. In ‘min_size’ mode, all the datasets reload when reaching the minimum length of datasets.

  • stochastic_weight_avg (bool) – Whether to use Stochastic Weight Averaging (SWA) <https://pytorch.org/blog/pytorch-1.6-now-includes-stochastic-weight-averaging/>_

fit(model, train_dataloaders=None, val_dataloaders=None, datamodule=None, train_dataloader=None)[source]

Runs the full optimization routine.

Parameters
Return type

None

predict(model=None, dataloaders=None, datamodule=None, return_predictions=None, ckpt_path='best')[source]

Separates from fit to make sure you never run on your predictions set until you want to. This will call the model forward function to compute predictions.

Parameters
Return type

Union[List[Any], List[List[Any]], None]

Returns

Returns a list of dictionaries, one for each provided dataloader containing their respective predictions.

test(model=None, dataloaders=None, ckpt_path='best', verbose=True, datamodule=None, test_dataloaders=None)[source]

Perform one evaluation epoch over the test set. It’s separated from fit to make sure you never run on your test set until you want to.

Parameters
Return type

List[Dict[str, float]]

Returns

List of dictionaries with metrics logged during the test phase, e.g., in model- or callback hooks like test_step(), test_epoch_end(), etc. The length of the list corresponds to the number of test dataloaders used.

tune(model, train_dataloaders=None, val_dataloaders=None, datamodule=None, scale_batch_size_kwargs=None, lr_find_kwargs=None, train_dataloader=None)[source]

Runs routines to tune hyperparameters before training.

Parameters
Return type

Dict[str, Union[int, _LRFinder, None]]

validate(model=None, dataloaders=None, ckpt_path='best', verbose=True, datamodule=None, val_dataloaders=None)[source]

Perform one evaluation epoch over the validation set.

Parameters
Return type

List[Dict[str, float]]

Returns

List of dictionaries with metrics logged during the validation phase, e.g., in model- or callback hooks like validation_step(), validation_epoch_end(), etc. The length of the list corresponds to the number of validation dataloaders used.

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