def stack(list_or_tensor, element_dtype=None, strict=True):
"""Stacks the input, if it admits the notion of stacking.
For example, a list of tensors can be stacked into a larger tensor. This
function is similar to tf.stack, but it accepts non-lists and lists of
non-tensors as arguments. In the latter case, the function does nothing.
Args:
list_or_tensor: Any
element_dtype: tf.DType, optional dtypedtype for the elements in the list.
Required if the input is stackable, and the list is untyped.
strict: bool, if True an error is raised if the input is not stackable.
Otherwise the function is a no-op.
Returns:
Any, if the input is stackable, the result will be a tf.Tensor. Otherwise,
if strict=False, the result will be list_or_tensor.
Raises:
ValueError: if strict=True and the input is not stackable.
"""
if strict:
def raise_error(x):
raise ValueError('%s must be stackable when strict=True' % x)
original_call = raise_error
else:
original_call = lambda x: x
return data_structures.list_stack(
list_or_tensor,
data_structures.ListStackOpts(element_dtype=element_dtype,
original_call=original_call))
def test_stack_fallback(self):
def dummy_function(l):
# Lazy person's mock: just transform the argument in a way in which we
# can check that this function was indeed called.
return [x * 2 for x in l]
opts = data_structures.ListStackOpts(element_dtype=None,
original_call=dummy_function)
self.assertAllEqual(data_structures.list_stack([1, 2], opts), [2, 4])
def test_stack_tensor_list(self):
initial_list = constant_op.constant([[1, 2], [3, 4]])
elem_shape = constant_op.constant([2])
l = list_ops.tensor_list_from_tensor(initial_list,
element_shape=elem_shape)
opts = data_structures.ListStackOpts(element_dtype=initial_list.dtype,
original_call=None)
with self.test_session() as sess:
t = data_structures.list_stack(l, opts)
self.assertAllEqual(sess.run(t), sess.run(initial_list))
def stack(list_or_tensor, element_dtype=None):
"""Stacks the input, if it admits the notion of stacking. No-op otherwise.
For example, a list of tensors can be stacked into a larger tensor. This
function is similar to tf.stack, but it accepts non-lists and lists of
non-tensors as arguments. In the latter case, the function does nothing.
Args:
list_or_tensor: Any entity.
element_dtype: Optional dtype for the elements in the list. Required if the
input is stackable, and the list is untyped.
Returns:
If the input is stackable, a new object representing the stacked inputs.
Otherwise it returns list_or_tensor unchanged.
"""
return data_structures.list_stack(
list_or_tensor,
data_structures.ListStackOpts(
element_dtype=element_dtype, original_call=lambda x: x))
