fix onlyconst for dataset with no features

autogl/module/feature/auto_feature.py

@@ -11,7 +11,7 @@ from .selectors import SeGBDT
 from . import register_feature
 
 from ...utils import get_logger
-
+import torch
 LOGGER = get_logger("Feature")
 
 
@@ -28,10 +28,13 @@ class Onlyconst(BaseFeatureEngineer):
     r"""it is a dummy feature engineer , which directly returns identical data"""
 
     def __init__(self, *args, **kwargs):
-        super(Onlyconst, self).__init__(multigraph=True, *args, **kwargs)
+        super(Onlyconst, self).__init__(data_t='tensor',multigraph=True, *args, **kwargs)
 
     def _transform(self, data):
-        data.x = np.ones((data.x.shape[0], 1))
+        if 'x' in data:
+            data.x = torch.ones((data.x.shape[0], 1))
+        else:
+            data.x= torch.ones((torch.unique(data.edge_index).shape[0],1))
         return data