# Copyright 2020 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.
# See the License for the specific language governing permissions and
# limitations under the License.
from monai.engines import Evaluator
from monai.utils import exact_version, optional_import
Events, _ = optional_import("ignite.engine", "0.3.0", exact_version, "Events")
Engine, _ = optional_import("ignite.engine", "0.3.0", exact_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.
"""
def __init__(self, validator: Evaluator, interval: int, epoch_level: bool = True) -> None: # type: ignore
"""
Args:
validator (Evaluator): run the validator when trigger validation, suppose to be Evaluator.
interval: do validation every N epochs or every N iterations during training.
epoch_level: execute validation every N epochs or N iterations.
`True` is epoch level, `False` is iteration level.
Raises:
ValueError: validator must be Evaluator ignite engine.
"""
if not isinstance(validator, Evaluator): # type: ignore
raise ValueError("validator must be Evaluator ignite engine.")
self.validator = validator
self.interval = interval
self.epoch_level = epoch_level
def attach(self, engine: Engine):
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):
self.validator.run(engine.state.epoch)