Source code for monai.handlers.stats_handler

# Copyright 2020 - 2021 MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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import logging
import warnings
from typing import TYPE_CHECKING, Any, Callable, Optional

import torch

from monai.utils import exact_version, is_scalar, optional_import

Events, _ = optional_import("ignite.engine", "0.4.2", exact_version, "Events")
if TYPE_CHECKING:
    from ignite.engine import Engine
else:
    Engine, _ = optional_import("ignite.engine", "0.4.2", exact_version, "Engine")

DEFAULT_KEY_VAL_FORMAT = "{}: {:.4f} "
DEFAULT_TAG = "Loss"


[docs]class StatsHandler(object): """ StatsHandler defines a set of Ignite Event-handlers for all the log printing logics. It's can be used for any Ignite Engine(trainer, validator and evaluator). And it can support logging for epoch level and iteration level with pre-defined loggers. Default behaviors: - When EPOCH_COMPLETED, logs ``engine.state.metrics`` using ``self.logger``. - When ITERATION_COMPLETED, logs ``self.output_transform(engine.state.output)`` using ``self.logger``. """ def __init__( self, epoch_print_logger: Optional[Callable[[Engine], Any]] = None, iteration_print_logger: Optional[Callable[[Engine], Any]] = None, output_transform: Callable = lambda x: x, global_epoch_transform: Callable = lambda x: x, name: Optional[str] = None, tag_name: str = DEFAULT_TAG, key_var_format: str = DEFAULT_KEY_VAL_FORMAT, logger_handler: Optional[logging.Handler] = None, ) -> None: """ Args: epoch_print_logger: customized callable printer for epoch level logging. Must accept parameter "engine", use default printer if None. iteration_print_logger: customized callable printer for iteration level logging. Must accept parameter "engine", use default printer if None. output_transform: a callable that is used to transform the ``ignite.engine.output`` into a scalar to print, or a dictionary of {key: scalar}. In the latter case, the output string will be formatted as key: value. By default this value logging happens when every iteration completed. global_epoch_transform: a callable that is used to customize global epoch number. For example, in evaluation, the evaluator engine might want to print synced epoch number with the trainer engine. name: identifier of logging.logger to use, defaulting to ``engine.logger``. tag_name: when iteration output is a scalar, tag_name is used to print tag_name: scalar_value to logger. Defaults to ``'Loss'``. key_var_format: a formatting string to control the output string format of key: value. logger_handler: add additional handler to handle the stats data: save to file, etc. Add existing python logging handlers: https://docs.python.org/3/library/logging.handlers.html """ self.epoch_print_logger = epoch_print_logger self.iteration_print_logger = iteration_print_logger self.output_transform = output_transform self.global_epoch_transform = global_epoch_transform self.logger = logging.getLogger(name) self._name = name self.tag_name = tag_name self.key_var_format = key_var_format if logger_handler is not None: self.logger.addHandler(logger_handler)
[docs] def attach(self, engine: Engine) -> None: """ Register a set of Ignite Event-Handlers to a specified Ignite engine. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. """ if self._name is None: self.logger = engine.logger if not engine.has_event_handler(self.iteration_completed, Events.ITERATION_COMPLETED): engine.add_event_handler(Events.ITERATION_COMPLETED, self.iteration_completed) if not engine.has_event_handler(self.epoch_completed, Events.EPOCH_COMPLETED): engine.add_event_handler(Events.EPOCH_COMPLETED, self.epoch_completed) if not engine.has_event_handler(self.exception_raised, Events.EXCEPTION_RAISED): engine.add_event_handler(Events.EXCEPTION_RAISED, self.exception_raised)
[docs] def epoch_completed(self, engine: Engine) -> None: """ Handler for train or validation/evaluation epoch completed Event. Print epoch level log, default values are from Ignite state.metrics dict. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. """ if self.epoch_print_logger is not None: self.epoch_print_logger(engine) else: self._default_epoch_print(engine)
[docs] def iteration_completed(self, engine: Engine) -> None: """ Handler for train or validation/evaluation iteration completed Event. Print iteration level log, default values are from Ignite state.logs dict. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. """ if self.iteration_print_logger is not None: self.iteration_print_logger(engine) else: self._default_iteration_print(engine)
[docs] def exception_raised(self, engine: Engine, e: Exception) -> None: """ Handler for train or validation/evaluation exception raised Event. Print the exception information and traceback. This callback may be skipped because the logic with Ignite can only trigger the first attached handler for `EXCEPTION_RAISED` event. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. e: the exception caught in Ignite during engine.run(). """ self.logger.exception(f"Exception: {e}") raise e
def _default_epoch_print(self, engine: Engine) -> None: """ Execute epoch level log operation based on Ignite engine.state data. print the values from Ignite state.metrics dict. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. """ prints_dict = engine.state.metrics if not prints_dict: return current_epoch = self.global_epoch_transform(engine.state.epoch) out_str = f"Epoch[{current_epoch}] Metrics -- " for name in sorted(prints_dict): value = prints_dict[name] out_str += self.key_var_format.format(name, value) self.logger.info(out_str) if hasattr(engine.state, "key_metric_name"): if hasattr(engine.state, "best_metric") and hasattr(engine.state, "best_metric_epoch"): out_str = f"Key metric: {engine.state.key_metric_name} " out_str += f"best value: {engine.state.best_metric} at epoch: {engine.state.best_metric_epoch}" self.logger.info(out_str) def _default_iteration_print(self, engine: Engine) -> None: """ Execute iteration log operation based on Ignite engine.state data. Print the values from Ignite state.logs dict. Default behavior is to print loss from output[1], skip if output[1] is not loss. Args: engine: Ignite Engine, it can be a trainer, validator or evaluator. """ loss = self.output_transform(engine.state.output) if loss is None: return # no printing if the output is empty out_str = "" if isinstance(loss, dict): # print dictionary items for name in sorted(loss): value = loss[name] if not is_scalar(value): warnings.warn( "ignoring non-scalar output in StatsHandler," " make sure `output_transform(engine.state.output)` returns" " a scalar or dictionary of key and scalar pairs to avoid this warning." " {}:{}".format(name, type(value)) ) continue # not printing multi dimensional output out_str += self.key_var_format.format(name, value.item() if torch.is_tensor(value) else value) else: if is_scalar(loss): # not printing multi dimensional output out_str += self.key_var_format.format(self.tag_name, loss.item() if torch.is_tensor(loss) else loss) else: warnings.warn( "ignoring non-scalar output in StatsHandler," " make sure `output_transform(engine.state.output)` returns" " a scalar or a dictionary of key and scalar pairs to avoid this warning." " {}".format(type(loss)) ) if not out_str: return # no value to print num_iterations = engine.state.epoch_length current_iteration = (engine.state.iteration - 1) % num_iterations + 1 current_epoch = engine.state.epoch num_epochs = engine.state.max_epochs base_str = f"Epoch: {current_epoch}/{num_epochs}, Iter: {current_iteration}/{num_iterations} --" self.logger.info(" ".join([base_str, out_str]))