Merge pull request #5557 from tensorflow/shizhiw_20181017

 Refactor neumf_model.py to support users who just need top_k and ndcg tensors.

official/recommendation/neumf_model.py

@@ -298,39 +298,8 @@ def compute_eval_loss_and_metrics(logits,              # type: tf.Tensor
   Returns:
     An EstimatorSpec for evaluation.
   """
-
-  logits_by_user = tf.reshape(logits, (-1, rconst.NUM_EVAL_NEGATIVES + 1))
-  duplicate_mask_by_user = tf.reshape(duplicate_mask,
-                                      (-1, rconst.NUM_EVAL_NEGATIVES + 1))
-
-  if match_mlperf:
-    # Set duplicate logits to the min value for that dtype. The MLPerf
-    # reference dedupes during evaluation.
-    logits_by_user *= (1 - duplicate_mask_by_user)
-    logits_by_user += duplicate_mask_by_user * logits_by_user.dtype.min
-
-  # Determine the location of the first element in each row after the elements
-  # are sorted.
-  sort_indices = tf.contrib.framework.argsort(
-      logits_by_user, axis=1, direction="DESCENDING")
-
-  # Use matrix multiplication to extract the position of the true item from the
-  # tensor of sorted indices. This approach is chosen because both GPUs and TPUs
-  # perform matrix multiplications very quickly. This is similar to np.argwhere.
-  # However this is a special case because the target will only appear in
-  # sort_indices once.
-  one_hot_position = tf.cast(tf.equal(sort_indices, 0), tf.int32)
-  sparse_positions = tf.multiply(
-      one_hot_position, tf.range(logits_by_user.shape[1])[tf.newaxis, :])
-  position_vector = tf.reduce_sum(sparse_positions, axis=1)
-
-  in_top_k = tf.cast(tf.less(position_vector, rconst.TOP_K), tf.float32)
-  ndcg = tf.log(2.) / tf.log(tf.cast(position_vector, tf.float32) + 2)
-  ndcg *= in_top_k
-
-  # If a row is a padded row, all but the first element will be a duplicate.
-  metric_weights = tf.not_equal(tf.reduce_sum(duplicate_mask_by_user, axis=1),
-                                rconst.NUM_EVAL_NEGATIVES)
+  in_top_k, ndcg, metric_weights, logits_by_user = compute_top_k_and_ndcg(
+      logits, duplicate_mask, match_mlperf)
 
   # Examples are provided by the eval Dataset in a structured format, so eval
   # labels can be reconstructed on the fly.
@@ -375,3 +344,60 @@ def compute_eval_loss_and_metrics(logits,              # type: tf.Tensor
       loss=cross_entropy,
       eval_metric_ops=metric_fn(in_top_k, ndcg, metric_weights)
   )
+
+
+def compute_top_k_and_ndcg(logits,              # type: tf.Tensor
+                           duplicate_mask,      # type: tf.Tensor
+                           match_mlperf=False   # type: bool
+                          ):
+  """Compute inputs of metric calculation.
+
+  Args:
+    logits: A tensor containing the predicted logits for each user. The shape
+      of logits is (num_users_per_batch * (1 + NUM_EVAL_NEGATIVES),) Logits
+      for a user are grouped, and the first element of the group is the true
+      element.
+    duplicate_mask: A vector with the same shape as logits, with a value of 1
+      if the item corresponding to the logit at that position has already
+      appeared for that user.
+    match_mlperf: Use the MLPerf reference convention for computing rank.
+
+  Returns:
+    is_top_k, ndcg and weights, all of which has size (num_users_in_batch,), and
+    logits_by_user which has size
+    (num_users_in_batch, (rconst.NUM_EVAL_NEGATIVES + 1)).
+  """
+  logits_by_user = tf.reshape(logits, (-1, rconst.NUM_EVAL_NEGATIVES + 1))
+  duplicate_mask_by_user = tf.reshape(duplicate_mask,
+                                      (-1, rconst.NUM_EVAL_NEGATIVES + 1))
+
+  if match_mlperf:
+    # Set duplicate logits to the min value for that dtype. The MLPerf
+    # reference dedupes during evaluation.
+    logits_by_user *= (1 - duplicate_mask_by_user)
+    logits_by_user += duplicate_mask_by_user * logits_by_user.dtype.min
+
+  # Determine the location of the first element in each row after the elements
+  # are sorted.
+  sort_indices = tf.contrib.framework.argsort(
+      logits_by_user, axis=1, direction="DESCENDING")
+
+  # Use matrix multiplication to extract the position of the true item from the
+  # tensor of sorted indices. This approach is chosen because both GPUs and TPUs
+  # perform matrix multiplications very quickly. This is similar to np.argwhere.
+  # However this is a special case because the target will only appear in
+  # sort_indices once.
+  one_hot_position = tf.cast(tf.equal(sort_indices, 0), tf.int32)
+  sparse_positions = tf.multiply(
+      one_hot_position, tf.range(logits_by_user.shape[1])[tf.newaxis, :])
+  position_vector = tf.reduce_sum(sparse_positions, axis=1)
+
+  in_top_k = tf.cast(tf.less(position_vector, rconst.TOP_K), tf.float32)
+  ndcg = tf.log(2.) / tf.log(tf.cast(position_vector, tf.float32) + 2)
+  ndcg *= in_top_k
+
+  # If a row is a padded row, all but the first element will be a duplicate.
+  metric_weights = tf.not_equal(tf.reduce_sum(duplicate_mask_by_user, axis=1),
+                                rconst.NUM_EVAL_NEGATIVES)
+
+  return in_top_k, ndcg, metric_weights, logits_by_user