ultralytics 8.0.44 export and task fixes (#1088)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Mehran Ghandehari <mehran.maps@gmail.com>
Co-authored-by: Laughing <61612323+Laughing-q@users.noreply.github.com>

ultralytics/nn/autobackend.py

@@ -181,7 +181,6 @@ class AutoBackend(nn.Module):
             import tensorflow as tf
             keras = False  # assume TF1 saved_model
             model = tf.keras.models.load_model(w) if keras else tf.saved_model.load(w)
-            w = Path(w) / 'metadata.yaml'
         elif pb:  # GraphDef https://www.tensorflow.org/guide/migrate#a_graphpb_or_graphpbtxt
             LOGGER.info(f'Loading {w} for TensorFlow GraphDef inference...')
             import tensorflow as tf
@@ -258,8 +257,9 @@ class AutoBackend(nn.Module):
                             f'\n\n{EXPORT_FORMATS_TABLE}')
 
         # Load external metadata YAML
+        w = Path(w)
         if xml or saved_model or paddle:
-            metadata = Path(w).parent / 'metadata.yaml'
+            metadata = (w if saved_model else w.parents[1] if paddle else w.parent) / 'metadata.yaml'
             if metadata.exists():
                 metadata = yaml_load(metadata)
                 stride, names = int(metadata['stride']), metadata['names']  # load metadata

ultralytics/nn/tasks.py

@@ -287,6 +287,7 @@ class ClassificationModel(BaseModel):
             LOGGER.info(f"Overriding model.yaml nc={self.yaml['nc']} with nc={nc}")
             self.yaml['nc'] = nc  # override yaml value
         self.model, self.save = parse_model(deepcopy(self.yaml), ch=ch, verbose=verbose)  # model, savelist
+        self.stride = torch.Tensor([1])  # no stride constraints
         self.names = {i: f'{i}' for i in range(self.yaml['nc'])}  # default names dict
         self.info()
 
@@ -520,14 +521,15 @@ def guess_model_task(model):
 
     # Guess from model filename
     if isinstance(model, (str, Path)):
-        model = Path(model).stem
-        if '-seg' in model:
+        model = Path(model)
+        if '-seg' in model.stem or 'segment' in model.parts:
             return 'segment'
-        elif '-cls' in model:
+        elif '-cls' in model.stem or 'classify' in model.parts:
             return 'classify'
-        else:
+        elif 'detect' in model.parts:
             return 'detect'
 
     # Unable to determine task from model
-    raise SyntaxError('YOLO is unable to automatically guess model task. Explicitly define task for your model, '
-                      "i.e. 'task=detect', 'task=segment' or 'task=classify'.")
+    LOGGER.warning("WARNING ⚠️ Unable to automatically guess model task, assuming 'task=detect'. "
+                   "Explicitly define task for your model, i.e. 'task=detect', 'task=segment' or 'task=classify'.")
+    return 'detect'  # assume detect