Avoid serializing generated thresholds for AUC metrics.

PiperOrigin-RevId: 381160816

keras/metrics.py

@@ -2116,6 +2116,7 @@ class AUC(Metric):
               summation_method, list(metrics_utils.AUCSummationMethod)))
 
     # Update properties.
+    self._init_from_thresholds = thresholds is not None
     if thresholds is not None:
       # If specified, use the supplied thresholds.
       self.num_thresholds = len(thresholds) + 2
@@ -2444,13 +2445,15 @@ class AUC(Metric):
         'num_thresholds': self.num_thresholds,
         'curve': self.curve.value,
         'summation_method': self.summation_method.value,
-        # We remove the endpoint thresholds as an inverse of how the thresholds
-        # were initialized. This ensures that a metric initialized from this
-        # config has the same thresholds.
-        'thresholds': self.thresholds[1:-1],
         'multi_label': self.multi_label,
         'label_weights': label_weights
     }
+    # optimization to avoid serializing a large number of generated thresholds
+    if self._init_from_thresholds:
+      # We remove the endpoint thresholds as an inverse of how the thresholds
+      # were initialized. This ensures that a metric initialized from this
+      # config has the same thresholds.
+      config['thresholds'] = self.thresholds[1:-1]
     base_config = super(AUC, self).get_config()
     return dict(list(base_config.items()) + list(config.items()))
 

keras/metrics_confusion_matrix_test.py

@@ -1237,6 +1237,7 @@ class AUCTest(tf.test.TestCase, parameterized.TestCase):
     self.assertEqual(auc_obj.summation_method,
                      metrics_utils.AUCSummationMethod.MAJORING)
     old_config = auc_obj.get_config()
+    self.assertNotIn('thresholds', old_config)
     self.assertDictEqual(old_config, json.loads(json.dumps(old_config)))
 
     # Check save and restore config.
@@ -1249,6 +1250,7 @@ class AUCTest(tf.test.TestCase, parameterized.TestCase):
     self.assertEqual(auc_obj2.summation_method,
                      metrics_utils.AUCSummationMethod.MAJORING)
     new_config = auc_obj2.get_config()
+    self.assertNotIn('thresholds', new_config)
     self.assertDictEqual(old_config, new_config)
     self.assertAllClose(auc_obj.thresholds, auc_obj2.thresholds)