Add expected_attention_loss_multiplier hparam to allow scaling the at…

…tention_loss.

PiperOrigin-RevId: 187549764

tensor2tensor/layers/common_attention.py

@@ -327,14 +327,17 @@ def add_standard_attention_hparams(hparams):
   return hparams
 
 
-def encoder_decoder_attention_loss(expected_attention, actual_attentions):
+def encoder_decoder_attention_loss(expected_attention,
+                                   actual_attentions,
+                                   loss_multiplier=1.0):
   """Computes encdec attention loss between expected and actual attentions.
 
   Args:
     expected_attention: Tensor storing the expected encoder-decoder attention
       weights with shape [batch_size, target_length, input_length].
     actual_attentions: Dictionary with actual attention weights for different
       attention types and hidden layers.
+    loss_multiplier: multiplier for the attention loss.
 
   Returns:
     MSE loss between the actual and expected attention weights.
@@ -351,8 +354,8 @@ def encoder_decoder_attention_loss(expected_attention, actual_attentions):
   # Reduce mean across all layers (axis=0) and all heads (axis=2) to get a
   # tensor with shape [batch_size, target_length, input_length].
   actual_attention_weights = tf.reduce_mean(actual_attention_weights, [0, 2])
-  return tf.losses.mean_squared_error(expected_attention,
-                                      actual_attention_weights)
+  return tf.losses.mean_squared_error(
+      expected_attention, actual_attention_weights) * loss_multiplier
 
 
 @expert_utils.add_name_scope()

tensor2tensor/models/transformer.py

@@ -176,7 +176,8 @@ def body(self, features):
     expected_attentions = features.get("expected_attentions")
     if expected_attentions is not None:
       attention_loss = common_attention.encoder_decoder_attention_loss(
-          expected_attentions, self.attention_weights)
+          expected_attentions, self.attention_weights,
+          hparams.expected_attention_loss_multiplier)
       return decoder_output, {"attention_loss": attention_loss}
 
     return decoder_output
@@ -1462,3 +1463,11 @@ def transformer_librispeech_tpu():
   librispeech.set_librispeech_length_hparams(hparams)
   return hparams
 
+
+@registry.register_hparams
+def transformer_supervised_attention():
+  """Hparams for supervised attention problems."""
+  hparams = transformer_base()
+  # Multiplier to the encoder-decoder expected attention loss.
+  hparams.add_hparam("expected_attention_loss_multiplier", 1.0)
+  return hparams

tensor2tensor/models/transformer_test.py

@@ -208,7 +208,8 @@ def testTransformerWithoutProblem(self):
         [BATCH_SIZE, TARGET_LENGTH, 1, hparams.hidden_size])
 
   def testTransformerWithEncoderDecoderAttentionLoss(self):
-    model, features = self.getModel(transformer.transformer_small())
+    model, features = self.getModel(
+        transformer.transformer_supervised_attention())
     expected_attention_weights = np.random.random_sample(
         size=(BATCH_SIZE, TARGET_LENGTH, INPUT_LENGTH))
     features["expected_attentions"] = tf.constant(