/
parsing_ops.py
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/
parsing_ops.py
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# Copyright 2018 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Experimental `dataset` API for parsing example."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from tensorflow.python.data.ops import dataset_ops
from tensorflow.python.data.util import structure
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import ops
from tensorflow.python.framework import sparse_tensor
from tensorflow.python.framework import tensor_spec
from tensorflow.python.ops import gen_experimental_dataset_ops
from tensorflow.python.ops import parsing_ops
from tensorflow.python.util.tf_export import tf_export
class _ParseExampleDataset(dataset_ops.UnaryDataset):
"""A `Dataset` that parses `example` dataset into a `dict` dataset."""
def __init__(self, input_dataset, features, num_parallel_calls):
self._input_dataset = input_dataset
if not structure.are_compatible(
input_dataset.element_spec,
tensor_spec.TensorSpec([None], dtypes.string)):
raise TypeError("Input dataset should be a dataset of vectors of strings")
self._num_parallel_calls = num_parallel_calls
# pylint: disable=protected-access
self._features = parsing_ops._prepend_none_dimension(features)
# sparse_keys and dense_keys come back sorted here.
(sparse_keys, sparse_types, dense_keys, dense_types, dense_defaults,
dense_shapes) = parsing_ops._features_to_raw_params(
self._features, [
parsing_ops.VarLenFeature, parsing_ops.SparseFeature,
parsing_ops.FixedLenFeature, parsing_ops.FixedLenSequenceFeature
])
# TODO(b/112859642): Pass sparse_index and sparse_values for SparseFeature.
(_, dense_defaults_vec, sparse_keys, sparse_types, dense_keys, dense_shapes,
dense_shape_as_shape) = parsing_ops._process_raw_parameters(
None, dense_defaults, sparse_keys, sparse_types, dense_keys,
dense_types, dense_shapes)
# pylint: enable=protected-access
self._sparse_keys = sparse_keys
self._sparse_types = sparse_types
self._dense_keys = dense_keys
self._dense_defaults = dense_defaults_vec
self._dense_shapes = dense_shapes
self._dense_types = dense_types
input_dataset_shape = dataset_ops.get_legacy_output_shapes(
self._input_dataset)
dense_output_shapes = [input_dataset_shape.concatenate(shape)
for shape in dense_shape_as_shape]
sparse_output_shapes = [input_dataset_shape.concatenate([None])
for _ in range(len(sparse_keys))]
output_shapes = dict(
zip(self._dense_keys + self._sparse_keys,
dense_output_shapes + sparse_output_shapes))
output_types = dict(
zip(self._dense_keys + self._sparse_keys,
self._dense_types + self._sparse_types))
output_classes = dict(
zip(self._dense_keys + self._sparse_keys,
[ops.Tensor for _ in range(len(self._dense_defaults))] +
[sparse_tensor.SparseTensor for _ in range(len(self._sparse_keys))
]))
self._element_spec = structure.convert_legacy_structure(
output_types, output_shapes, output_classes)
variant_tensor = (
gen_experimental_dataset_ops.parse_example_dataset(
self._input_dataset._variant_tensor, # pylint: disable=protected-access
self._num_parallel_calls,
self._dense_defaults,
self._sparse_keys,
self._dense_keys,
self._sparse_types,
self._dense_shapes,
**self._flat_structure))
super(_ParseExampleDataset, self).__init__(input_dataset, variant_tensor)
@property
def element_spec(self):
return self._element_spec
# TODO(b/111553342): add arguments names and example names as well.
@tf_export("data.experimental.parse_example_dataset")
def parse_example_dataset(features, num_parallel_calls=1):
"""A transformation that parses `Example` protos into a `dict` of tensors.
Parses a number of serialized `Example` protos given in `serialized`. We refer
to `serialized` as a batch with `batch_size` many entries of individual
`Example` protos.
This op parses serialized examples into a dictionary mapping keys to `Tensor`
and `SparseTensor` objects. `features` is a dict from keys to `VarLenFeature`,
`SparseFeature`, and `FixedLenFeature` objects. Each `VarLenFeature`
and `SparseFeature` is mapped to a `SparseTensor`, and each
`FixedLenFeature` is mapped to a `Tensor`. See `tf.io.parse_example` for more
details about feature dictionaries.
Args:
features: A `dict` mapping feature keys to `FixedLenFeature`,
`VarLenFeature`, and `SparseFeature` values.
num_parallel_calls: (Optional.) A `tf.int32` scalar `tf.Tensor`,
representing the number of parsing processes to call in parallel.
Returns:
A dataset transformation function, which can be passed to
`tf.data.Dataset.apply`.
Raises:
ValueError: if features argument is None.
"""
if features is None:
raise ValueError("Missing: features was %s." % features)
def _apply_fn(dataset):
"""Function from `Dataset` to `Dataset` that applies the transformation."""
out_dataset = _ParseExampleDataset(dataset, features, num_parallel_calls)
if any(
isinstance(feature, parsing_ops.SparseFeature)
for _, feature in features.items()
):
# pylint: disable=protected-access
# pylint: disable=g-long-lambda
out_dataset = out_dataset.map(
lambda x: parsing_ops._construct_sparse_tensors_for_sparse_features(
features, x), num_parallel_calls=num_parallel_calls)
return out_dataset
return _apply_fn