1# Copyright 2017 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"""Scan dataset transformation.""" 16from __future__ import absolute_import 17from __future__ import division 18from __future__ import print_function 19 20from tensorflow.python.util import deprecation 21from tensorflow.python.util.tf_export import tf_export 22 23 24@deprecation.deprecated(None, "Use `tf.data.Dataset.scan(...) instead") 25@tf_export("data.experimental.scan") 26def scan(initial_state, scan_func): 27 """A transformation that scans a function across an input dataset. 28 29 This transformation is a stateful relative of `tf.data.Dataset.map`. 30 In addition to mapping `scan_func` across the elements of the input dataset, 31 `scan()` accumulates one or more state tensors, whose initial values are 32 `initial_state`. 33 34 Args: 35 initial_state: A nested structure of tensors, representing the initial state 36 of the accumulator. 37 scan_func: A function that maps `(old_state, input_element)` to 38 `(new_state, output_element)`. It must take two arguments and return a 39 pair of nested structures of tensors. The `new_state` must match the 40 structure of `initial_state`. 41 42 Returns: 43 A `Dataset` transformation function, which can be passed to 44 `tf.data.Dataset.apply`. 45 """ 46 def _apply_fn(dataset): 47 return dataset.scan(initial_state=initial_state, scan_func=scan_func) 48 49 return _apply_fn 50