General refactoring and improvements (#373)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/yolo/v8/detect/train.py

@@ -197,7 +197,7 @@ class Loss:
 
 @hydra.main(version_base=None, config_path=str(DEFAULT_CONFIG.parent), config_name=DEFAULT_CONFIG.name)
 def train(cfg):
-    cfg.model = cfg.model or "yolov8n.yaml"
+    cfg.model = cfg.model or "yolov8n.pt"
     cfg.data = cfg.data or "coco128.yaml"  # or yolo.ClassificationDataset("mnist")
     cfg.device = cfg.device if cfg.device is not None else ''
     # trainer = DetectionTrainer(cfg)
@@ -208,11 +208,4 @@ def train(cfg):
 
 
 if __name__ == "__main__":
-    """
-    CLI usage:
-    python ultralytics/yolo/v8/detect/train.py model=yolov8n.yaml data=coco128 epochs=100 imgsz=640
-
-    TODO:
-    yolo task=detect mode=train model=yolov8n.yaml data=coco128.yaml epochs=100
-    """
     train()

ultralytics/yolo/v8/detect/val.py

@@ -234,6 +234,7 @@ class DetectionValidator(BaseValidator):
 
 @hydra.main(version_base=None, config_path=str(DEFAULT_CONFIG.parent), config_name=DEFAULT_CONFIG.name)
 def val(cfg):
+    cfg.model = cfg.model or "yolov8n.pt"
     cfg.data = cfg.data or "coco128.yaml"
     validator = DetectionValidator(args=cfg)
     validator(model=cfg.model)