fix memory issue

PanopticQuality.py

@@ -105,7 +105,7 @@ class PQMetric(evaluate.Metric):
                             'MARITIME_ANIMAL': 18}
         
         DEFAULT_STUFF = ["WATER", "SKY", "LAND", "CONSTRUCTION", "ICE", "OWN_BOAT"]
-        
+
         self.label2id = label2id if label2id is not None else DEFAULT_LABEL2ID
         self.stuff =  stuff if stuff is not None else DEFAULT_STUFF
         self.pq_metric = PanopticQuality(
@@ -173,14 +173,6 @@ class PQMetric(evaluate.Metric):
 
     def _postprocess(self, np_array):
         """Converts the numpy arrays to lists for type checking"""
-        return self._np_to_lists(np_array)
-
-    def _np_to_lists(self, d):
-        """datasets does not support numpy arrays for type checking"""
-        if isinstance(d, np.ndarray):
-            if d.ndim == 1:
-                return d.tolist()
-            else:
-                return [self._np_to_lists(sub_arr) for sub_arr in d]
-        else:
-            return d
+        # add fake data to avoid out of memory problem
+        # only reuqired for interface, not used by metric anyway
+        return np.zeros((1,1,1,1)).tolist()