more advanced loss function for the model

Author: GreenWizard2015

Core/CModelTrainer.py

@@ -40,26 +40,52 @@ def _pointLoss(self, ytrue, ypred):
     tf.assert_equal(tf.shape(loss), tf.shape(ytrue))
     return tf.reduce_mean(loss, axis=-1)
 
-  def _trainStep(self, Data):
-    print('Instantiate _trainStep')
-    ###############
-    x, (y, ) = Data
-    y = y[..., 0, :]
-    losses = {}
-    with tf.GradientTape() as tape:
-      data = x['augmented']
+  def _trainOn(self, data, y_list):
+      def calculate_loss(predictions):
+        # select the smallest loss from the list of suggested points
+        losses = []
+        for y in y_list:
+          loss = self._pointLoss(y, predictions)[..., None]
+          losses.append(loss)
+          continue
+        losses = tf.concat(losses, axis=-1)
+        shp = tf.shape(y_list[0])
+        tf.assert_equal(tf.shape(losses), tf.concat([shp[:-1], [len(y_list)]], axis=0))
+        losses = tf.reduce_min(losses, axis=-1)
+        tf.assert_equal(tf.shape(losses), shp[:-1])
+        return tf.reduce_mean(losses)
+      
       data = self._replaceByEmbeddings(data)
       predictions = self._model(data, training=True)
       intermediate = predictions['intermediate']
-      losses['final'] = tf.reduce_mean(self._pointLoss(y, predictions['result']))
+      finalPredictions = predictions['result']
+      losses = {}
+      losses['final'] = calculate_loss(finalPredictions)
       for name, encoder in self._intermediateEncoders.items():
         latent = intermediate[name]
         pts = encoder(latent, training=True)
-        loss = self._pointLoss(y, pts)
+        loss = calculate_loss(pts)
         losses['loss-%s' % name] = tf.reduce_mean(loss)
         continue
-      loss = sum(losses.values())
-      losses['loss'] = loss
+      return losses, tf.stop_gradient(finalPredictions)
+    
+  def _trainStep(self, Data):
+    print('Instantiate _trainStep')
+    ###############
+    x, (y, ) = Data
+    y = y[..., 0, :]
+    losses = {}
+    with tf.GradientTape() as tape:
+      lossesClean, y_clean = self._trainOn(x['clean'], [y])
+      # ensure that the augmentations are not affect predictions
+      lossesAugmented, _ = self._trainOn(x['augmented'], [y, y_clean])
+      assert lossesClean.keys() == lossesAugmented.keys(), 'Losses keys mismatch'
+      # combine losses
+      losses = {k: lossesClean[k] + lossesAugmented[k] for k in lossesClean.keys()}
+      # calculate total loss and final loss
+      losses['total-clean'] = sum(lossesClean.values())
+      losses['total-augmented'] = sum(lossesAugmented.values())
+      losses['loss'] = loss = sum([losses['total-clean'], losses['total-augmented']])
 
     self._optimizer.minimize(loss, tape.watched_variables(), tape=tape)
     ###############