Support Iterables in ops.convert_n_to_tensor_or_indexed_slices and math_ops.add_n.

Fixes a tf.add_n papercut where it cannot be used with common iterable types beyond list/tuple. It only iterates the collection once, so it need not be any more specific than requiring an iterable.

PiperOrigin-RevId: 314477113
Change-Id: I9bc1d2d3b2296e72f085d23481738df616b0ec6c

tensorflow/python/framework/indexed_slices.py

@@ -327,8 +327,8 @@ def internal_convert_n_to_tensor_or_indexed_slices(values,
   unmodified.
 
   Args:
-    values: A list of `None`, `IndexedSlices`, `SparseTensor`, or objects that
+    values: An iterable of `None`, `IndexedSlices`, `SparseTensor`, or objects
-      can be consumed by `convert_to_tensor()`.
+      that can be consumed by `convert_to_tensor()`.
     dtype: (Optional.) The required `DType` of the returned `Tensor` or
       `IndexedSlices`.
     name: (Optional.) A name prefix to used when a new `Tensor` is created, in
@@ -344,8 +344,8 @@ def internal_convert_n_to_tensor_or_indexed_slices(values,
     RuntimeError: If a registered conversion function returns an invalid
       value.
   """
-  if not isinstance(values, collections.Sequence):
+  if not isinstance(values, collections.Iterable):
-    raise TypeError("values must be a sequence.")
+    raise TypeError("values must be iterable.")
   ret = []
   for i, value in enumerate(values):
     if value is None:

tensorflow/python/ops/math_ops.py

@@ -70,6 +70,8 @@ from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
 
+import collections
+
 import numpy as np
 import six
 from six.moves import builtins
@@ -3421,12 +3423,12 @@ def add_n(inputs, name=None):
     ValueError: If `inputs` don't all have same shape and dtype or the shape
     cannot be inferred.
   """
-  if not inputs or not isinstance(inputs, (list, tuple)):
+  if not inputs or not isinstance(inputs, collections.Iterable):
-    raise ValueError("inputs must be a list of at least one "
+    raise ValueError("inputs must be an iterable of at least one "
                      "Tensor/IndexedSlices with the same dtype and shape")
   inputs = ops.convert_n_to_tensor_or_indexed_slices(inputs)
   if not all(isinstance(x, (ops.Tensor, ops.IndexedSlices)) for x in inputs):
-    raise ValueError("inputs must be a list of at least one "
+    raise ValueError("inputs must be an iterable of at least one "
                      "Tensor/IndexedSlices with the same dtype and shape")
 
   if len(inputs) == 1:

tensorflow/python/ops/math_ops_test.py

@@ -423,6 +423,16 @@ class AddNTest(test_util.TensorFlowTestCase):
       self.assertAllEqual(slc_as_dense, math_ops.add_n([slc]))
       self.assertAllEqual(2 * slc_as_dense, math_ops.add_n([slc, slc]))
 
+  def test_iterable(self):
+    """Test that add_n supports iterables (e.g. generators and dict values)."""
+    def fn():
+      yield 1
+      yield 2
+    values_dict = {"a": 1, "b": 2}
+    with test_util.use_gpu():
+      self.assertAllEqual(3, math_ops.add_n(fn()))
+      self.assertAllEqual(3, math_ops.add_n(values_dict.values()))
+
 
 @test_util.run_all_in_graph_and_eager_modes
 class DivAndModTest(test_util.TensorFlowTestCase):