1# Copyright 2021 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"""Python API for random indexing into a dataset.""" 16 17from __future__ import absolute_import 18from __future__ import division 19from __future__ import print_function 20 21from tensorflow.python.data.util import structure 22from tensorflow.python.ops import gen_experimental_dataset_ops 23 24 25def at(dataset, index): 26 """Returns the element at a specific index in a datasest. 27 28 Args: 29 dataset: A `tf.data.Dataset` to determine whether it supports random access. 30 index: The index at which to fetch the element. 31 32 Returns: 33 A (nested) structure of values matching `tf.data.Dataset.element_spec`. 34 35 Raises: 36 UnimplementedError: If random access is not yet supported for a dataset. 37 """ 38 # pylint: disable=protected-access 39 return structure.from_tensor_list( 40 dataset.element_spec, 41 gen_experimental_dataset_ops.get_element_at_index( 42 dataset, 43 index, 44 output_types=dataset._flat_types, 45 output_shapes=dataset._flat_shapes)) 46