Fix processing of QM9EdgeDataset (#2801)

python/dgl/data/qm9_edge.py

@@ -135,7 +135,7 @@ class QM9EdgeDataset(DGLDataset):
                  raw_dir=None, 
                  force_reload=False, 
                  verbose=True):
-        if label_keys == None:
+        if label_keys is None:
             self.label_keys = None
             self.num_labels = 19
         else:
@@ -157,23 +157,7 @@ class QM9EdgeDataset(DGLDataset):
             download(self._url, path=file_path)
     
     def process(self):
-
-        npz_path = f'{self.raw_dir}/qm9_edge.npz'
-    
-        data_dict = np.load(npz_path, allow_pickle=True)
-
-        self.n_node = data_dict['n_node']
-        self.n_edge = data_dict['n_edge']
-        self.node_attr = data_dict['node_attr']
-        self.node_pos = data_dict['node_pos']
-        self.edge_attr = data_dict['edge_attr']
-        self.target = data_dict['target']
-        
-        self.src = data_dict['src']
-        self.dst = data_dict['dst']
-        
-        self.n_cumsum = np.concatenate([[0], np.cumsum(self.n_node)])
-        self.ne_cumsum = np.concatenate([[0], np.cumsum(self.n_edge)])
+        self.load()
 
     def has_cache(self):
         npz_path = f'{self.raw_dir}/qm9_edge.npz'