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# Ultralytics YOLO 🚀, AGPL-3.0 license
import torch
from ultralytics.yolo.data import ClassificationDataset, build_dataloader
from ultralytics.yolo.engine.validator import BaseValidator
from ultralytics.yolo.utils import DEFAULT_CFG, LOGGER
from ultralytics.yolo.utils.metrics import ClassifyMetrics, ConfusionMatrix
from ultralytics.yolo.utils.plotting import plot_images
class ClassificationValidator(BaseValidator):
def __init__(self, dataloader=None, save_dir=None, pbar=None, args=None, _callbacks=None):
"""Initializes ClassificationValidator instance with args, dataloader, save_dir, and progress bar."""
super().__init__(dataloader, save_dir, pbar, args, _callbacks)
self.args.task = 'classify'
self.metrics = ClassifyMetrics()
def get_desc(self):
"""Returns a formatted string summarizing classification metrics."""
return ('%22s' + '%11s' * 2) % ('classes', 'top1_acc', 'top5_acc')
def init_metrics(self, model):
"""Initialize confusion matrix, class names, and top-1 and top-5 accuracy."""
self.names = model.names
self.nc = len(model.names)
self.confusion_matrix = ConfusionMatrix(nc=self.nc, task='classify')
self.pred = []
self.targets = []
def preprocess(self, batch):
"""Preprocesses input batch and returns it."""
batch['img'] = batch['img'].to(self.device, non_blocking=True)
batch['img'] = batch['img'].half() if self.args.half else batch['img'].float()
batch['cls'] = batch['cls'].to(self.device)
return batch
def update_metrics(self, preds, batch):
"""Updates running metrics with model predictions and batch targets."""
n5 = min(len(self.model.names), 5)
self.pred.append(preds.argsort(1, descending=True)[:, :n5])
self.targets.append(batch['cls'])
def finalize_metrics(self, *args, **kwargs):
"""Finalizes metrics of the model such as confusion_matrix and speed."""
self.confusion_matrix.process_cls_preds(self.pred, self.targets)
if self.args.plots:
self.confusion_matrix.plot(save_dir=self.save_dir, names=list(self.names.values()))
self.metrics.speed = self.speed
self.metrics.confusion_matrix = self.confusion_matrix
def get_stats(self):
"""Returns a dictionary of metrics obtained by processing targets and predictions."""
self.metrics.process(self.targets, self.pred)
return self.metrics.results_dict
def build_dataset(self, img_path):
dataset = ClassificationDataset(root=img_path, imgsz=self.args.imgsz, augment=False)
return dataset
def get_dataloader(self, dataset_path, batch_size):
"""Builds and returns a data loader for classification tasks with given parameters."""
dataset = self.build_dataset(dataset_path)
return build_dataloader(dataset, batch_size, self.args.workers, rank=-1)
def print_results(self):
"""Prints evaluation metrics for YOLO object detection model."""
pf = '%22s' + '%11.3g' * len(self.metrics.keys) # print format
LOGGER.info(pf % ('all', self.metrics.top1, self.metrics.top5))
def plot_val_samples(self, batch, ni):
"""Plot validation image samples."""
plot_images(images=batch['img'],
batch_idx=torch.arange(len(batch['img'])),
cls=batch['cls'].squeeze(-1),
fname=self.save_dir / f'val_batch{ni}_labels.jpg',
names=self.names)
def plot_predictions(self, batch, preds, ni):
"""Plots predicted bounding boxes on input images and saves the result."""
plot_images(batch['img'],
batch_idx=torch.arange(len(batch['img'])),
cls=torch.argmax(preds, dim=1),
fname=self.save_dir / f'val_batch{ni}_pred.jpg',
names=self.names) # pred
def val(cfg=DEFAULT_CFG, use_python=False):
"""Validate YOLO model using custom data."""
model = cfg.model or 'yolov8n-cls.pt' # or "resnet18"
data = cfg.data or 'mnist160'
args = dict(model=model, data=data)
if use_python:
from ultralytics import YOLO
YOLO(model).val(**args)
else:
validator = ClassificationValidator(args=args)
validator(model=args['model'])
if __name__ == '__main__':
val()