def _finalize_func(string_handle):
"""Destroys the iterator resource created.
Args:
string_handle: An iterator string handle created by _init_func
Returns:
Tensor constant 0
"""
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
**self._input_dataset._flat_structure) # pylint: disable=protected-access
with ops.control_dependencies([
resource_variable_ops.destroy_resource_op(
iterator_resource, ignore_lookup_error=True)]):
return array_ops.constant(0, dtypes.int64)
def _finalize_func(string_handle):
"""Destroys the iterator resource created.
Args:
string_handle: An iterator string handle created by _init_func
Returns:
Tensor constant 0
"""
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
**dataset_ops.flat_structure(self._input_dataset))
with ops.control_dependencies([
resource_variable_ops.destroy_resource_op(
iterator_resource, ignore_lookup_error=True)]):
return array_ops.constant(0, dtypes.int64)
def _finalize_func(string_handle):
"""Destroys the iterator resource created.
Args:
string_handle: An iterator string handle created by _init_func
Returns:
Tensor constant 0
"""
iterator_resource = core_gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
output_types=self._flat_output_types,
output_shapes=self._flat_output_shapes)
with ops.control_dependencies([
resource_variable_ops.destroy_resource_op(
iterator_resource, ignore_lookup_error=True)]):
return array_ops.constant(0, dtypes.int64)
def from_string_handle(string_handle,
output_types,
output_shapes=None,
output_classes=None):
"""Creates a new, uninitialized `Iterator` based on the given handle.
This method allows you to define a "feedable" iterator where you can choose
between concrete iterators by feeding a value in a `tf.Session.run` call.
In that case, `string_handle` would be a `tf.compat.v1.placeholder`, and you
would
feed it with the value of `tf.data.Iterator.string_handle` in each step.
For example, if you had two iterators that marked the current position in
a training dataset and a test dataset, you could choose which to use in
each step as follows:
```python
train_iterator = tf.data.Dataset(...).make_one_shot_iterator()
train_iterator_handle = sess.run(train_iterator.string_handle())
test_iterator = tf.data.Dataset(...).make_one_shot_iterator()
test_iterator_handle = sess.run(test_iterator.string_handle())
handle = tf.compat.v1.placeholder(tf.string, shape=[])
iterator = tf.data.Iterator.from_string_handle(
handle, train_iterator.output_types)
next_element = iterator.get_next()
loss = f(next_element)
train_loss = sess.run(loss, feed_dict={handle: train_iterator_handle})
test_loss = sess.run(loss, feed_dict={handle: test_iterator_handle})
```
Args:
string_handle: A scalar `tf.Tensor` of type `tf.string` that evaluates to
a handle produced by the `Iterator.string_handle()` method.
output_types: A nested structure of `tf.DType` objects corresponding to
each component of an element of this dataset.
output_shapes: (Optional.) A nested structure of `tf.TensorShape` objects
corresponding to each component of an element of this dataset. If
omitted, each component will have an unconstrainted shape.
output_classes: (Optional.) A nested structure of Python `type` objects
corresponding to each component of an element of this iterator. If
omitted, each component is assumed to be of type `tf.Tensor`.
Returns:
An `Iterator`.
"""
output_types = nest.map_structure(dtypes.as_dtype, output_types)
if output_shapes is None:
output_shapes = nest.map_structure(
lambda _: tensor_shape.TensorShape(None), output_types)
else:
output_shapes = nest.map_structure_up_to(output_types,
tensor_shape.as_shape,
output_shapes)
if output_classes is None:
output_classes = nest.map_structure(lambda _: ops.Tensor,
output_types)
nest.assert_same_structure(output_types, output_shapes)
output_structure = structure.convert_legacy_structure(
output_types, output_shapes, output_classes)
string_handle = ops.convert_to_tensor(string_handle,
dtype=dtypes.string)
if _device_stack_is_empty():
with ops.device("/cpu:0"):
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
output_types=structure.get_flat_tensor_types(
output_structure),
output_shapes=structure.get_flat_tensor_shapes(
output_structure))
else:
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
output_types=structure.get_flat_tensor_types(output_structure),
output_shapes=structure.get_flat_tensor_shapes(
output_structure))
return Iterator(iterator_resource, None, output_types, output_shapes,
output_classes)
def from_string_handle(string_handle,
output_types,
output_shapes=None,
output_classes=None):
"""Creates a new, uninitialized `Iterator` based on the given handle.
This method allows you to define a "feedable" iterator where you can choose
between concrete iterators by feeding a value in a `tf.Session.run` call.
In that case, `string_handle` would be a `tf.placeholder`, and you would
feed it with the value of `tf.data.Iterator.string_handle` in each step.
For example, if you had two iterators that marked the current position in
a training dataset and a test dataset, you could choose which to use in
each step as follows:
```python
train_iterator = tf.data.Dataset(...).make_one_shot_iterator()
train_iterator_handle = sess.run(train_iterator.string_handle())
test_iterator = tf.data.Dataset(...).make_one_shot_iterator()
test_iterator_handle = sess.run(test_iterator.string_handle())
handle = tf.placeholder(tf.string, shape=[])
iterator = tf.data.Iterator.from_string_handle(
handle, train_iterator.output_types)
next_element = iterator.get_next()
loss = f(next_element)
train_loss = sess.run(loss, feed_dict={handle: train_iterator_handle})
test_loss = sess.run(loss, feed_dict={handle: test_iterator_handle})
```
Args:
string_handle: A scalar `tf.Tensor` of type `tf.string` that evaluates
to a handle produced by the `Iterator.string_handle()` method.
output_types: A nested structure of `tf.DType` objects corresponding to
each component of an element of this dataset.
output_shapes: (Optional.) A nested structure of `tf.TensorShape` objects
corresponding to each component of an element of this dataset. If
omitted, each component will have an unconstrainted shape.
output_classes: (Optional.) A nested structure of Python `type` objects
corresponding to each component of an element of this iterator. If
omitted, each component is assumed to be of type `tf.Tensor`.
Returns:
An `Iterator`.
"""
output_types = nest.map_structure(dtypes.as_dtype, output_types)
if output_shapes is None:
output_shapes = nest.map_structure(
lambda _: tensor_shape.TensorShape(None), output_types)
else:
output_shapes = nest.map_structure_up_to(
output_types, tensor_shape.as_shape, output_shapes)
if output_classes is None:
output_classes = nest.map_structure(lambda _: ops.Tensor, output_types)
nest.assert_same_structure(output_types, output_shapes)
output_structure = structure_lib.convert_legacy_structure(
output_types, output_shapes, output_classes)
string_handle = ops.convert_to_tensor(string_handle, dtype=dtypes.string)
# pylint: disable=protected-access
if compat.forward_compatible(2018, 8, 3):
if _device_stack_is_empty():
with ops.device("/cpu:0"):
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
output_types=output_structure._flat_types,
output_shapes=output_structure._flat_shapes)
else:
iterator_resource = gen_dataset_ops.iterator_from_string_handle_v2(
string_handle,
output_types=output_structure._flat_types,
output_shapes=output_structure._flat_shapes)
else:
iterator_resource = gen_dataset_ops.iterator_from_string_handle(
string_handle,
output_types=output_structure._flat_types,
output_shapes=output_structure._flat_shapes)
# pylint: enable=protected-access
return Iterator(iterator_resource, None, output_types, output_shapes,
output_classes)
