Update app.py

app.py

@@ -115,11 +115,13 @@ def test(input_json):
 
     
     art = result_dict["DRT"]
-    
-    
+          
     df_art_matrix = pd.DataFrame(art).T
     df_art_matrix = df_art_matrix.round(0).astype(int)    
 
+    if df_art_matrix.empty():
+        print("transport matrix is empty")
+    
     
     # create a mask based on the matrix size and ids, crop activity nodes to the mask
     mask_connected = df_matrix.index.tolist()