_construct_sparse_tensors_for_sparse_features returns a new dictionary instead of modifying the one passed in.

Change: 143819066

1 files changed, 15 insertions, 9 deletions

diff --git a/tensorflow/python/ops/parsing_ops.py b/tensorflow/python/ops/parsing_ops.py
index 6e7b0fe083..079837bce3 100644
--- a/tensorflow/python/ops/parsing_ops.py
+++ b/tensorflow/python/ops/parsing_ops.py
@@ -206,10 +206,12 @@ def _features_to_raw_params(features, types):
 def _construct_sparse_tensors_for_sparse_features(features, tensor_dict):
   """Merges SparseTensors of indices and values of SparseFeatures.
 
-  Updates `tensor_dict`. For `SparseFeatures` in the values of `features`
-  expects their `index_key`s and `index_value`s to be present in `tensor_dict`
-  mapping to `SparseTensor`s. Removes those, constructs a single `SparseTensor`
-  from them, and adds it to `tensor_dict` with the key from `features`.
+  Constructs new dict based on `tensor_dict`. For `SparseFeatures` in the values
+  of `features` expects their `index_key`s and `index_value`s to be present in
+  `tensor_dict` mapping to `SparseTensor`s. Constructs a single `SparseTensor`
+  from them, and adds it to the result with the key from `features`.
+  Copies other keys and values from `tensor_dict` with keys present in
+  `features`.
 
   Args:
     features: A `dict` mapping feature keys to `SparseFeature` values.
@@ -217,7 +219,12 @@ def _construct_sparse_tensors_for_sparse_features(features, tensor_dict):
     tensor_dict: A `dict` mapping feature keys to `Tensor` and `SparseTensor`
       values. Expected to contain keys of the `SparseFeature`s' `index_key`s and
       `value_key`s and mapping them to `SparseTensor`s.
+  Returns:
+    A `dict` mapping feature keys to `Tensor` and `SparseTensor` values. Similar
+    to `tensor_dict` except each `SparseFeature`s in `features` results in a
+    single `SparseTensor`.
   """
+  tensor_dict = dict(tensor_dict)  # Do not modify argument passed in.
   # Construct SparseTensors for SparseFeatures.
   for key in sorted(features.keys()):
     feature = features[key]
@@ -231,8 +238,9 @@ def _construct_sparse_tensors_for_sparse_features(features, tensor_dict):
           already_sorted=feature.already_sorted)
   # Remove tensors from dictionary that were only used to construct
   # SparseTensors for SparseFeature.
-  for key in set(tensor_dict.keys()) - set(features.keys()):
+  for key in set(tensor_dict) - set(features):
     del tensor_dict[key]
+  return tensor_dict
 
 
 def parse_example(serialized, features, name=None, example_names=None):
@@ -435,8 +443,7 @@ def parse_example(serialized, features, name=None, example_names=None):
   outputs = _parse_example_raw(
       serialized, example_names, sparse_keys, sparse_types, dense_keys,
       dense_types, dense_defaults, dense_shapes, name)
-  _construct_sparse_tensors_for_sparse_features(features, outputs)
-  return outputs
+  return _construct_sparse_tensors_for_sparse_features(features, outputs)
 
 
 def _parse_example_raw(serialized,
@@ -586,8 +593,7 @@ def parse_single_example(serialized, features, name=None, example_names=None):
   outputs = _parse_single_example_raw(
       serialized, example_names, sparse_keys, sparse_types, dense_keys,
       dense_types, dense_defaults, dense_shapes, name)
-  _construct_sparse_tensors_for_sparse_features(features, outputs)
-  return outputs
+  return _construct_sparse_tensors_for_sparse_features(features, outputs)
 
 
 def _parse_single_example_raw(serialized,