Merge pull request #3744 from suiyuan2009/fix-py_func-length-1

extract element from list when py_func's output type is a single tensorflow type

tensorflow/python/kernel_tests/py_func_test.py

@@ -34,6 +34,13 @@ class PyOpTest(tf.test.TestCase):
     def my_func(x, y):
       return np.sinh(x) + np.cosh(y)
 
+    # single type
+    with self.test_session():
+      x = tf.constant(1.0, tf.float32)
+      y = tf.constant(2.0, tf.float32)
+      z = tf.py_func(my_func, [x, y], tf.float32)
+      self.assertEqual(z.eval(), my_func(1.0, 2.0).astype(np.float32))
+
     # scalar
     with self.test_session():
       x = tf.constant(1.0, tf.float32)

tensorflow/python/ops/script_ops.py

@@ -132,8 +132,8 @@ def py_func(func, inp, Tout, stateful=True, name=None):
   Args:
     func: A python function.
     inp: A list of `Tensor`.
-    Tout: A list of tensorflow data types indicating what `func`
-          returns.
+    Tout: A list of tensorflow data types or a single tensorflow data type
+          indicating what `func` returns.
     stateful: A boolean indicating whether the function should be considered
               stateful or stateless. I.e. whether it, given the same input, will
               return the same output and at the same time does not change state
@@ -142,7 +142,7 @@ def py_func(func, inp, Tout, stateful=True, name=None):
     name: A name for the operation (optional).
 
   Returns:
-    A list of `Tensor` which `func` computes.
+    A list of `Tensor` or a single `Tensor` which `func` computes.
   """
   token = _py_funcs.insert(func)
   # We tie the registered function's life-time with the current
@@ -162,14 +162,20 @@ def py_func(func, inp, Tout, stateful=True, name=None):
   # the funcs registry.
   g._cleanup_py_funcs_used_in_graph.append(cleanup)
 
+  if isinstance(Tout, list):
+    is_list = True
+  else:
+    Tout = [Tout]
+    is_list = False
   if stateful:
-    return gen_script_ops._py_func(input=inp, token=token, Tout=Tout, name=name)
+    result = gen_script_ops._py_func(
+            input=inp, token=token, Tout=Tout, name=name)
     # pylint: enable=protected-access
   else:
-    return gen_script_ops._py_func_stateless(
-        input=inp, token=token, Tout=Tout,
-        name=name)
+    result = gen_script_ops._py_func_stateless(
+        input=inp, token=token, Tout=Tout, name=name)
     # pylint: enable=protected-access
+  return result if is_list else result[0]
 
 
 ops.RegisterShape("PyFunc")(common_shapes.unknown_shape)