Source code for monai.handlers.validation_handler
# Copyright (c) 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
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from typing import TYPE_CHECKING, Optional
from monai.config import IgniteInfo
from monai.engines.evaluator import Evaluator
from monai.utils import min_version, optional_import
Events, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Events")
if TYPE_CHECKING:
from ignite.engine import Engine
else:
Engine, _ = optional_import("ignite.engine", IgniteInfo.OPT_IMPORT_VERSION, min_version, "Engine")
[docs]class ValidationHandler:
"""
Attach validator to the trainer engine in Ignite.
It can support to execute validation every N epochs or every N iterations.
"""
[docs] def __init__(self, interval: int, validator: Optional[Evaluator] = None, epoch_level: bool = True) -> None:
"""
Args:
interval: do validation every N epochs or every N iterations during training.
validator: run the validator when trigger validation, suppose to be Evaluator.
if None, should call `set_validator()` before training.
epoch_level: execute validation every N epochs or N iterations.
`True` is epoch level, `False` is iteration level.
Raises:
TypeError: When ``validator`` is not a ``monai.engines.evaluator.Evaluator``.
"""
if validator is not None and not isinstance(validator, Evaluator):
raise TypeError(f"validator must be a monai.engines.evaluator.Evaluator but is {type(validator).__name__}.")
self.validator = validator
self.interval = interval
self.epoch_level = epoch_level
[docs] def set_validator(self, validator: Evaluator):
"""
Set validator if not setting in the __init__().
"""
if not isinstance(validator, Evaluator):
raise TypeError(f"validator must be a monai.engines.evaluator.Evaluator but is {type(validator).__name__}.")
self.validator = validator
[docs] def attach(self, engine: Engine) -> None:
"""
Args:
engine: Ignite Engine, it can be a trainer, validator or evaluator.
"""
if self.epoch_level:
engine.add_event_handler(Events.EPOCH_COMPLETED(every=self.interval), self)
else:
engine.add_event_handler(Events.ITERATION_COMPLETED(every=self.interval), self)
def __call__(self, engine: Engine) -> None:
"""
Args:
engine: Ignite Engine, it can be a trainer, validator or evaluator.
"""
if self.validator is None:
raise RuntimeError("please set validator in __init__() or call `set_validator()` before training.")
self.validator.run(engine.state.epoch)