[bugfix]: fix bug of softmax_loss_with_negative_mining loss (#237)

* [bugfix]: fix bug of softmax_loss_with_negative_mining loss

easy_rec/python/loss/softmax_loss_with_negative_mining.py

@@ -2,8 +2,6 @@
 # Copyright (c) Alibaba, Inc. and its affiliates.
 import tensorflow as tf
 
-from easy_rec.python.utils.shape_utils import get_shape_list
-
 if tf.__version__ >= '2.0':
   tf = tf.compat.v1
 
@@ -65,33 +63,36 @@ def softmax_loss_with_negative_mining(user_emb,
   Return:
     support vector guided softmax loss of positive labels
   """
-  batch_size = get_shape_list(item_emb)[0]
-  assert 0 < num_negative_samples < batch_size, '`num_negative_samples` should be in range [1, batch_size)'
+  assert 0 < num_negative_samples, '`num_negative_samples` should be greater than 0'
 
-  if not embed_normed:
-    user_emb = tf.nn.l2_normalize(user_emb, axis=-1)
-    item_emb = tf.nn.l2_normalize(item_emb, axis=-1)
+  batch_size = tf.shape(item_emb)[0]
+  is_valid = tf.assert_less(num_negative_samples, batch_size,
+                            message='`num_negative_samples` should be less than batch_size')
+  with tf.control_dependencies([is_valid]):
+    if not embed_normed:
+      user_emb = tf.nn.l2_normalize(user_emb, axis=-1)
+      item_emb = tf.nn.l2_normalize(item_emb, axis=-1)
 
-  vectors = [item_emb]
-  for i in range(num_negative_samples):
-    shift = tf.random_uniform([], 1, batch_size, dtype=tf.int32)
-    neg_item_emb = tf.roll(item_emb, shift, axis=0)
-    vectors.append(neg_item_emb)
-  # all_embeddings's shape: (batch_size, num_negative_samples + 1, vec_dim)
-  all_embeddings = tf.stack(vectors, axis=1)
+    vectors = [item_emb]
+    for i in range(num_negative_samples):
+      shift = tf.random_uniform([], 1, batch_size, dtype=tf.int32)
+      neg_item_emb = tf.roll(item_emb, shift, axis=0)
+      vectors.append(neg_item_emb)
+    # all_embeddings's shape: (batch_size, num_negative_samples + 1, vec_dim)
+    all_embeddings = tf.stack(vectors, axis=1)
 
-  mask = tf.greater(labels, 0)
-  mask_user_emb = tf.boolean_mask(user_emb, mask)
-  mask_item_emb = tf.boolean_mask(all_embeddings, mask)
-  if isinstance(weights, tf.Tensor):
-    weights = tf.boolean_mask(weights, mask)
+    mask = tf.greater(labels, 0)
+    mask_user_emb = tf.boolean_mask(user_emb, mask)
+    mask_item_emb = tf.boolean_mask(all_embeddings, mask)
+    if isinstance(weights, tf.Tensor):
+      weights = tf.boolean_mask(weights, mask)
 
-  # sim_scores's shape: (num_of_pos_label_in_batch_size, num_negative_samples + 1)
-  sim_scores = tf.keras.backend.batch_dot(
-      mask_user_emb, mask_item_emb, axes=(1, 2))
-  pos_score = tf.slice(sim_scores, [0, 0], [-1, 1])
-  neg_scores = tf.slice(sim_scores, [0, 1], [-1, -1])
+    # sim_scores's shape: (num_of_pos_label_in_batch_size, num_negative_samples + 1)
+    sim_scores = tf.keras.backend.batch_dot(
+        mask_user_emb, mask_item_emb, axes=(1, 2))
+    pos_score = tf.slice(sim_scores, [0, 0], [-1, 1])
+    neg_scores = tf.slice(sim_scores, [0, 1], [-1, -1])
 
-  loss = support_vector_guided_softmax_loss(
-      pos_score, neg_scores, margin=margin, t=t, smooth=gamma, weights=weights)
+    loss = support_vector_guided_softmax_loss(
+        pos_score, neg_scores, margin=margin, t=t, smooth=gamma, weights=weights)
   return loss

easy_rec/python/test/loss_test.py

@@ -26,19 +26,20 @@ def test_f1_reweighted_loss(self):
 
   def test_softmax_loss_with_negative_mining(self):
     print('test_softmax_loss_with_negative_mining')
-    user_emb = tf.constant([[0.1, 0.5, 0.3], [0.8, -0.1, 0.3], [0.28, 0.3, 0.9],
-                            [0.37, 0.45, 0.93], [-0.7, 0.15, 0.03],
-                            [0.18, 0.9, -0.3]])
+    user_emb = tf.constant([[0.1, 0.5, 0.3], [0.8, -0.1, 0.3],
+                            [0.28, 0.3, 0.9], [0.37, 0.45, 0.93],
+                            [-0.7, 0.15, 0.03], [0.18, 0.9, -0.3]])
     item_emb = tf.constant([[0.1, -0.5, 0.3], [0.8, -0.31, 0.3],
                             [0.7, -0.45, 0.15], [0.08, -0.31, -0.9],
                             [-0.7, 0.85, 0.03], [0.18, 0.89, -0.3]])
 
     label = tf.constant([1, 1, 0, 0, 1, 1])
+    tf.random.set_random_seed(1)
     loss = softmax_loss_with_negative_mining(
-        user_emb, item_emb, label, num_negative_samples=1)
+        user_emb, item_emb, label, num_negative_samples=2)
     with self.test_session() as sess:
       loss_val = sess.run(loss)
-      self.assertAlmostEqual(loss_val, 0.5240243, delta=1e-5)
+      self.assertAlmostEqual(loss_val, 0.76977473, delta=1e-5)
 
   def test_circle_loss(self):
     print('test_circle_loss')