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Validator

All task Validators are inherited from BaseValidator class that contains the model validation routine boilerplate. You can override any function of these Trainers to suit your needs.


BaseValidator API Reference

BaseValidator

A base class for creating validators.

Attributes:

Name Type Description
dataloader DataLoader

Dataloader to use for validation.

pbar tqdm

Progress bar to update during validation.

logger logging.Logger

Logger to use for validation.

args SimpleNamespace

Configuration for the validator.

model nn.Module

Model to validate.

data dict

Data dictionary.

device torch.device

Device to use for validation.

batch_i int

Current batch index.

training bool

Whether the model is in training mode.

speed float

Batch processing speed in seconds.

jdict dict

Dictionary to store validation results.

save_dir Path

Directory to save results.

Source code in ultralytics/yolo/engine/validator.py
class BaseValidator:
    """
    BaseValidator

    A base class for creating validators.

    Attributes:
        dataloader (DataLoader): Dataloader to use for validation.
        pbar (tqdm): Progress bar to update during validation.
        logger (logging.Logger): Logger to use for validation.
        args (SimpleNamespace): Configuration for the validator.
        model (nn.Module): Model to validate.
        data (dict): Data dictionary.
        device (torch.device): Device to use for validation.
        batch_i (int): Current batch index.
        training (bool): Whether the model is in training mode.
        speed (float): Batch processing speed in seconds.
        jdict (dict): Dictionary to store validation results.
        save_dir (Path): Directory to save results.
    """

    def __init__(self, dataloader=None, save_dir=None, pbar=None, logger=None, args=None):
        """
        Initializes a BaseValidator instance.

        Args:
            dataloader (torch.utils.data.DataLoader): Dataloader to be used for validation.
            save_dir (Path): Directory to save results.
            pbar (tqdm.tqdm): Progress bar for displaying progress.
            logger (logging.Logger): Logger to log messages.
            args (SimpleNamespace): Configuration for the validator.
        """
        self.dataloader = dataloader
        self.pbar = pbar
        self.logger = logger or LOGGER
        self.args = args or get_cfg(DEFAULT_CFG)
        self.model = None
        self.data = None
        self.device = None
        self.batch_i = None
        self.training = True
        self.speed = None
        self.jdict = None

        project = self.args.project or Path(SETTINGS['runs_dir']) / self.args.task
        name = self.args.name or f"{self.args.mode}"
        self.save_dir = save_dir or increment_path(Path(project) / name,
                                                   exist_ok=self.args.exist_ok if RANK in {-1, 0} else True)
        (self.save_dir / 'labels' if self.args.save_txt else self.save_dir).mkdir(parents=True, exist_ok=True)

        if self.args.conf is None:
            self.args.conf = 0.001  # default conf=0.001

        self.callbacks = defaultdict(list, callbacks.default_callbacks)  # add callbacks

    @smart_inference_mode()
    def __call__(self, trainer=None, model=None):
        """
        Supports validation of a pre-trained model if passed or a model being trained
        if trainer is passed (trainer gets priority).
        """
        self.training = trainer is not None
        if self.training:
            self.device = trainer.device
            self.data = trainer.data
            model = trainer.ema.ema or trainer.model
            self.args.half = self.device.type != 'cpu'  # force FP16 val during training
            model = model.half() if self.args.half else model.float()
            self.model = model
            self.loss = torch.zeros_like(trainer.loss_items, device=trainer.device)
            self.args.plots = trainer.epoch == trainer.epochs - 1  # always plot final epoch
            model.eval()
        else:
            callbacks.add_integration_callbacks(self)
            self.run_callbacks('on_val_start')
            assert model is not None, "Either trainer or model is needed for validation"
            self.device = select_device(self.args.device, self.args.batch)
            self.args.half &= self.device.type != 'cpu'
            model = AutoBackend(model, device=self.device, dnn=self.args.dnn, fp16=self.args.half)
            self.model = model
            stride, pt, jit, engine = model.stride, model.pt, model.jit, model.engine
            imgsz = check_imgsz(self.args.imgsz, stride=stride)
            if engine:
                self.args.batch = model.batch_size
            else:
                self.device = model.device
                if not pt and not jit:
                    self.args.batch = 1  # export.py models default to batch-size 1
                    self.logger.info(
                        f'Forcing --batch-size 1 square inference (1,3,{imgsz},{imgsz}) for non-PyTorch models')

            if isinstance(self.args.data, str) and self.args.data.endswith(".yaml"):
                self.data = check_det_dataset(self.args.data)
            elif self.args.task == 'classify':
                self.data = check_cls_dataset(self.args.data)
            else:
                raise FileNotFoundError(emojis(f"Dataset '{self.args.data}' not found ❌"))

            if self.device.type == 'cpu':
                self.args.workers = 0  # faster CPU val as time dominated by inference, not dataloading
            self.dataloader = self.dataloader or \
                              self.get_dataloader(self.data.get("val") or self.data.set("test"), self.args.batch)

            model.eval()
            model.warmup(imgsz=(1 if pt else self.args.batch, 3, imgsz, imgsz))  # warmup

        dt = Profile(), Profile(), Profile(), Profile()
        n_batches = len(self.dataloader)
        desc = self.get_desc()
        # NOTE: keeping `not self.training` in tqdm will eliminate pbar after segmentation evaluation during training,
        # which may affect classification task since this arg is in yolov5/classify/val.py.
        # bar = tqdm(self.dataloader, desc, n_batches, not self.training, bar_format=TQDM_BAR_FORMAT)
        bar = tqdm(self.dataloader, desc, n_batches, bar_format=TQDM_BAR_FORMAT)
        self.init_metrics(de_parallel(model))
        self.jdict = []  # empty before each val
        for batch_i, batch in enumerate(bar):
            self.run_callbacks('on_val_batch_start')
            self.batch_i = batch_i
            # pre-process
            with dt[0]:
                batch = self.preprocess(batch)

            # inference
            with dt[1]:
                preds = model(batch["img"])

            # loss
            with dt[2]:
                if self.training:
                    self.loss += trainer.criterion(preds, batch)[1]

            # pre-process predictions
            with dt[3]:
                preds = self.postprocess(preds)

            self.update_metrics(preds, batch)
            if self.args.plots and batch_i < 3:
                self.plot_val_samples(batch, batch_i)
                self.plot_predictions(batch, preds, batch_i)

            self.run_callbacks('on_val_batch_end')
        stats = self.get_stats()
        self.check_stats(stats)
        self.print_results()
        self.speed = tuple(x.t / len(self.dataloader.dataset) * 1E3 for x in dt)  # speeds per image
        self.run_callbacks('on_val_end')
        if self.training:
            model.float()
            results = {**stats, **trainer.label_loss_items(self.loss.cpu() / len(self.dataloader), prefix="val")}
            return {k: round(float(v), 5) for k, v in results.items()}  # return results as 5 decimal place floats
        else:
            self.logger.info('Speed: %.1fms pre-process, %.1fms inference, %.1fms loss, %.1fms post-process per image' %
                             self.speed)
            if self.args.save_json and self.jdict:
                with open(str(self.save_dir / "predictions.json"), 'w') as f:
                    self.logger.info(f"Saving {f.name}...")
                    json.dump(self.jdict, f)  # flatten and save
                stats = self.eval_json(stats)  # update stats
            return stats

    def run_callbacks(self, event: str):
        for callback in self.callbacks.get(event, []):
            callback(self)

    def get_dataloader(self, dataset_path, batch_size):
        raise NotImplementedError("get_dataloader function not implemented for this validator")

    def preprocess(self, batch):
        return batch

    def postprocess(self, preds):
        return preds

    def init_metrics(self, model):
        pass

    def update_metrics(self, preds, batch):
        pass

    def get_stats(self):
        return {}

    def check_stats(self, stats):
        pass

    def print_results(self):
        pass

    def get_desc(self):
        pass

    @property
    def metric_keys(self):
        return []

    # TODO: may need to put these following functions into callback
    def plot_val_samples(self, batch, ni):
        pass

    def plot_predictions(self, batch, preds, ni):
        pass

    def pred_to_json(self, preds, batch):
        pass

    def eval_json(self, stats):
        pass

__call__(trainer=None, model=None)

Supports validation of a pre-trained model if passed or a model being trained if trainer is passed (trainer gets priority).

Source code in ultralytics/yolo/engine/validator.py
@smart_inference_mode()
def __call__(self, trainer=None, model=None):
    """
    Supports validation of a pre-trained model if passed or a model being trained
    if trainer is passed (trainer gets priority).
    """
    self.training = trainer is not None
    if self.training:
        self.device = trainer.device
        self.data = trainer.data
        model = trainer.ema.ema or trainer.model
        self.args.half = self.device.type != 'cpu'  # force FP16 val during training
        model = model.half() if self.args.half else model.float()
        self.model = model
        self.loss = torch.zeros_like(trainer.loss_items, device=trainer.device)
        self.args.plots = trainer.epoch == trainer.epochs - 1  # always plot final epoch
        model.eval()
    else:
        callbacks.add_integration_callbacks(self)
        self.run_callbacks('on_val_start')
        assert model is not None, "Either trainer or model is needed for validation"
        self.device = select_device(self.args.device, self.args.batch)
        self.args.half &= self.device.type != 'cpu'
        model = AutoBackend(model, device=self.device, dnn=self.args.dnn, fp16=self.args.half)
        self.model = model
        stride, pt, jit, engine = model.stride, model.pt, model.jit, model.engine
        imgsz = check_imgsz(self.args.imgsz, stride=stride)
        if engine:
            self.args.batch = model.batch_size
        else:
            self.device = model.device
            if not pt and not jit:
                self.args.batch = 1  # export.py models default to batch-size 1
                self.logger.info(
                    f'Forcing --batch-size 1 square inference (1,3,{imgsz},{imgsz}) for non-PyTorch models')

        if isinstance(self.args.data, str) and self.args.data.endswith(".yaml"):
            self.data = check_det_dataset(self.args.data)
        elif self.args.task == 'classify':
            self.data = check_cls_dataset(self.args.data)
        else:
            raise FileNotFoundError(emojis(f"Dataset '{self.args.data}' not found ❌"))

        if self.device.type == 'cpu':
            self.args.workers = 0  # faster CPU val as time dominated by inference, not dataloading
        self.dataloader = self.dataloader or \
                          self.get_dataloader(self.data.get("val") or self.data.set("test"), self.args.batch)

        model.eval()
        model.warmup(imgsz=(1 if pt else self.args.batch, 3, imgsz, imgsz))  # warmup

    dt = Profile(), Profile(), Profile(), Profile()
    n_batches = len(self.dataloader)
    desc = self.get_desc()
    # NOTE: keeping `not self.training` in tqdm will eliminate pbar after segmentation evaluation during training,
    # which may affect classification task since this arg is in yolov5/classify/val.py.
    # bar = tqdm(self.dataloader, desc, n_batches, not self.training, bar_format=TQDM_BAR_FORMAT)
    bar = tqdm(self.dataloader, desc, n_batches, bar_format=TQDM_BAR_FORMAT)
    self.init_metrics(de_parallel(model))
    self.jdict = []  # empty before each val
    for batch_i, batch in enumerate(bar):
        self.run_callbacks('on_val_batch_start')
        self.batch_i = batch_i
        # pre-process
        with dt[0]:
            batch = self.preprocess(batch)

        # inference
        with dt[1]:
            preds = model(batch["img"])

        # loss
        with dt[2]:
            if self.training:
                self.loss += trainer.criterion(preds, batch)[1]

        # pre-process predictions
        with dt[3]:
            preds = self.postprocess(preds)

        self.update_metrics(preds, batch)
        if self.args.plots and batch_i < 3:
            self.plot_val_samples(batch, batch_i)
            self.plot_predictions(batch, preds, batch_i)

        self.run_callbacks('on_val_batch_end')
    stats = self.get_stats()
    self.check_stats(stats)
    self.print_results()
    self.speed = tuple(x.t / len(self.dataloader.dataset) * 1E3 for x in dt)  # speeds per image
    self.run_callbacks('on_val_end')
    if self.training:
        model.float()
        results = {**stats, **trainer.label_loss_items(self.loss.cpu() / len(self.dataloader), prefix="val")}
        return {k: round(float(v), 5) for k, v in results.items()}  # return results as 5 decimal place floats
    else:
        self.logger.info('Speed: %.1fms pre-process, %.1fms inference, %.1fms loss, %.1fms post-process per image' %
                         self.speed)
        if self.args.save_json and self.jdict:
            with open(str(self.save_dir / "predictions.json"), 'w') as f:
                self.logger.info(f"Saving {f.name}...")
                json.dump(self.jdict, f)  # flatten and save
            stats = self.eval_json(stats)  # update stats
        return stats

__init__(dataloader=None, save_dir=None, pbar=None, logger=None, args=None)

Initializes a BaseValidator instance.

Parameters:

Name Type Description Default
dataloader torch.utils.data.DataLoader

Dataloader to be used for validation.

None
save_dir Path

Directory to save results.

None
pbar tqdm.tqdm

Progress bar for displaying progress.

None
logger logging.Logger

Logger to log messages.

None
args SimpleNamespace

Configuration for the validator.

None
Source code in ultralytics/yolo/engine/validator.py
def __init__(self, dataloader=None, save_dir=None, pbar=None, logger=None, args=None):
    """
    Initializes a BaseValidator instance.

    Args:
        dataloader (torch.utils.data.DataLoader): Dataloader to be used for validation.
        save_dir (Path): Directory to save results.
        pbar (tqdm.tqdm): Progress bar for displaying progress.
        logger (logging.Logger): Logger to log messages.
        args (SimpleNamespace): Configuration for the validator.
    """
    self.dataloader = dataloader
    self.pbar = pbar
    self.logger = logger or LOGGER
    self.args = args or get_cfg(DEFAULT_CFG)
    self.model = None
    self.data = None
    self.device = None
    self.batch_i = None
    self.training = True
    self.speed = None
    self.jdict = None

    project = self.args.project or Path(SETTINGS['runs_dir']) / self.args.task
    name = self.args.name or f"{self.args.mode}"
    self.save_dir = save_dir or increment_path(Path(project) / name,
                                               exist_ok=self.args.exist_ok if RANK in {-1, 0} else True)
    (self.save_dir / 'labels' if self.args.save_txt else self.save_dir).mkdir(parents=True, exist_ok=True)

    if self.args.conf is None:
        self.args.conf = 0.001  # default conf=0.001

    self.callbacks = defaultdict(list, callbacks.default_callbacks)  # add callbacks