Simplify thop imports (#18717)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>

ultralytics/nn/modules/block.py

@@ -1131,7 +1131,7 @@ class TorchVision(nn.Module):
 
     def __init__(self, c1, c2, model, weights="DEFAULT", unwrap=True, truncate=2, split=False):
         """Load the model and weights from torchvision."""
-        import torchvision
+        import torchvision  # scope for faster 'import ultralytics'
 
         super().__init__()
         if hasattr(torchvision.models, "get_model"):

ultralytics/nn/tasks.py

@@ -7,6 +7,7 @@ import types
 from copy import deepcopy
 from pathlib import Path
 
+import thop
 import torch
 import torch.nn as nn
 
@@ -86,11 +87,6 @@ from ultralytics.utils.torch_utils import (
     time_sync,
 )
 
-try:
-    import thop
-except ImportError:
-    thop = None
-
 
 class BaseModel(nn.Module):
     """The BaseModel class serves as a base class for all the models in the Ultralytics YOLO family."""