xref: /aosp_15_r20/external/tensorflow/tensorflow/python/data/experimental/ops/cardinality.py (revision b6fb3261f9314811a0f4371741dbb8839866f948) 
1# Copyright 2018 The TensorFlow Authors. All Rights Reserved.
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14# ==============================================================================
15"""Cardinality analysis of `Dataset` objects."""
16from tensorflow.python.data.ops import dataset_ops
17from tensorflow.python.framework import dtypes
18from tensorflow.python.framework import ops
19from tensorflow.python.ops import gen_dataset_ops
20from tensorflow.python.ops import gen_experimental_dataset_ops as ged_ops
21from tensorflow.python.util.tf_export import tf_export
22
23
24INFINITE = -1
25UNKNOWN = -2
26tf_export("data.experimental.INFINITE_CARDINALITY").export_constant(
27    __name__, "INFINITE")
28tf_export("data.experimental.UNKNOWN_CARDINALITY").export_constant(
29    __name__, "UNKNOWN")
30
31
32# TODO(b/157691652): Deprecate this method after migrating users to the new API.
33@tf_export("data.experimental.cardinality")
34def cardinality(dataset):
35  """Returns the cardinality of `dataset`, if known.
36
37  The operation returns the cardinality of `dataset`. The operation may return
38  `tf.data.experimental.INFINITE_CARDINALITY` if `dataset` contains an infinite
39  number of elements or `tf.data.experimental.UNKNOWN_CARDINALITY` if the
40  analysis fails to determine the number of elements in `dataset` (e.g. when the
41  dataset source is a file).
42
43  >>> dataset = tf.data.Dataset.range(42)
44  >>> print(tf.data.experimental.cardinality(dataset).numpy())
45  42
46  >>> dataset = dataset.repeat()
47  >>> cardinality = tf.data.experimental.cardinality(dataset)
48  >>> print((cardinality == tf.data.experimental.INFINITE_CARDINALITY).numpy())
49  True
50  >>> dataset = dataset.filter(lambda x: True)
51  >>> cardinality = tf.data.experimental.cardinality(dataset)
52  >>> print((cardinality == tf.data.experimental.UNKNOWN_CARDINALITY).numpy())
53  True
54
55  Args:
56    dataset: A `tf.data.Dataset` for which to determine cardinality.
57
58  Returns:
59    A scalar `tf.int64` `Tensor` representing the cardinality of `dataset`. If
60    the cardinality is infinite or unknown, the operation returns the named
61    constant `INFINITE_CARDINALITY` and `UNKNOWN_CARDINALITY` respectively.
62  """
63
64  return gen_dataset_ops.dataset_cardinality(dataset._variant_tensor)  # pylint: disable=protected-access
65
66
67@tf_export("data.experimental.assert_cardinality")
68def assert_cardinality(expected_cardinality):
69  """Asserts the cardinality of the input dataset.
70
71  NOTE: The following assumes that "examples.tfrecord" contains 42 records.
72
73  >>> dataset = tf.data.TFRecordDataset("examples.tfrecord")
74  >>> cardinality = tf.data.experimental.cardinality(dataset)
75  >>> print((cardinality == tf.data.experimental.UNKNOWN_CARDINALITY).numpy())
76  True
77  >>> dataset = dataset.apply(tf.data.experimental.assert_cardinality(42))
78  >>> print(tf.data.experimental.cardinality(dataset).numpy())
79  42
80
81  Args:
82    expected_cardinality: The expected cardinality of the input dataset.
83
84  Returns:
85    A `Dataset` transformation function, which can be passed to
86    `tf.data.Dataset.apply`.
87
88  Raises:
89    FailedPreconditionError: The assertion is checked at runtime (when iterating
90      the dataset) and an error is raised if the actual and expected cardinality
91      differ.
92  """
93  def _apply_fn(dataset):
94    return _AssertCardinalityDataset(dataset, expected_cardinality)
95
96  return _apply_fn
97
98
99class _AssertCardinalityDataset(dataset_ops.UnaryUnchangedStructureDataset):
100  """A `Dataset` that assert the cardinality of its input."""
101
102  def __init__(self, input_dataset, expected_cardinality):
103    self._input_dataset = input_dataset
104    self._expected_cardinality = ops.convert_to_tensor(
105        expected_cardinality, dtype=dtypes.int64, name="expected_cardinality")
106
107    # pylint: enable=protected-access
108    variant_tensor = ged_ops.assert_cardinality_dataset(
109        self._input_dataset._variant_tensor,  # pylint: disable=protected-access
110        self._expected_cardinality,
111        **self._flat_structure)
112    super(_AssertCardinalityDataset, self).__init__(input_dataset,
113                                                    variant_tensor)
114