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Update docs for tf.data.experimental.TFRecordWriter

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PiperOrigin-RevId: 272008952
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Andrew Audibert 2019-09-30 10:14:25 -07:00 committed by TensorFlower Gardener
parent 028c82a779
commit 8569d12747
1 changed files with 34 additions and 6 deletions
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40
tensorflow/python/data/experimental/ops/writers.py
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@ -28,16 +28,25 @@ from tensorflow.python.util.tf_export import tf_export
@tf_export("data.experimental.TFRecordWriter")
class TFRecordWriter(object):
"""Writes data to a TFRecord file.
"""Writes a dataset to a TFRecord file.
To write a `dataset` to a single TFRecord file:
The elements of the dataset must be scalar strings. To serialize dataset
elements as strings, you can use the `tf.io.serialize_tensor` function.
```python
dataset = ... # dataset to be written
writer = tf.data.experimental.TFRecordWriter(PATH)
dataset = tf.data.Dataset.range(3)
dataset = dataset.map(tf.io.serialize_tensor)
writer = tf.data.experimental.TFRecordWriter("/path/to/file.tfrecord")
writer.write(dataset)
```
To read back the elements, use `TFRecordDataset`.
```python
dataset = tf.data.TFRecordDataset("/path/to/file.tfrecord")
dataset = dataset.map(lambda x: tf.io.parse_tensor(x, tf.int64))
```
To shard a `dataset` across multiple TFRecord files:
```python
@ -57,6 +66,14 @@ class TFRecordWriter(object):
"""
def __init__(self, filename, compression_type=None):
"""Initializes a `TFRecordWriter`.
Args:
filename: a string path indicating where to write the TFRecord data.
compression_type: (Optional.) a string indicating what type of compression
to use when writing the file. See `tf.io.TFRecordCompressionType` for
what types of compression are available. Defaults to `None`.
"""
self._filename = ops.convert_to_tensor(
filename, dtypes.string, name="filename")
self._compression_type = convert.optional_param_to_tensor(
@ -66,13 +83,24 @@ class TFRecordWriter(object):
argument_dtype=dtypes.string)
def write(self, dataset):
"""Returns a `tf.Operation` to write a dataset to a file.
"""Writes a dataset to a TFRecord file.
An operation that writes the content of the specified dataset to the file
specified in the constructor.
If the file exists, it will be overwritten.
Args:
dataset: a `tf.data.Dataset` whose elements are to be written to a file
Returns:
A `tf.Operation` that, when run, writes contents of `dataset` to a file.
In graph mode, this returns an operation which when executed performs the
write. In eager mode, the write is performed by the method itself and
there is no return value.
Raises
TypeError: if `dataset` is not a `tf.data.Dataset`.
TypeError: if the elements produced by the dataset are not scalar strings.
"""
if not isinstance(dataset, dataset_ops.DatasetV2):
raise TypeError("`dataset` must be a `tf.data.Dataset` object.")