tf.io / SparseFeature

See Stable See Nightly

TensorFlow 1 version

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A class to write records to a TFRecords file.

tf.io.TFRecordWriter(
    path, options=None
)

Used in the notebooks

TFRecords tutorial

TFRecords is a binary format which is optimized for high throughput data retrieval, generally in conjunction with tf.data. TFRecordWriter is used to write serialized examples to a file for later consumption. The key steps are:

Ahead of time:

• Convert data into a serialized format

• Write the serialized data to one or more files

  During training or evaluation:

• Read serialized examples into memory

• Parse (deserialize) examples

A minimal example is given below:

import tempfile
example_path = os.path.join(tempfile.gettempdir(), "example.tfrecords")
np.random.seed(0)

# Write the records to a file.
with tf.io.TFRecordWriter(example_path) as file_writer:
  for _ in range(4):
    x, y = np.random.random(), np.random.random()

    record_bytes = tf.train.Example(features=tf.train.Features(feature={
        "x": tf.train.Feature(float_list=tf.train.FloatList(value=[x])),
        "y": tf.train.Feature(float_list=tf.train.FloatList(value=[y])),
    })).SerializeToString()
    file_writer.write(record_bytes)

# Read the data back out.
def decode_fn(record_bytes):
  return tf.io.parse_single_example(
      # Data
      record_bytes,

      # Schema
      {"x": tf.io.FixedLenFeature([], dtype=tf.float32),
       "y": tf.io.FixedLenFeature([], dtype=tf.float32)}
  )

for batch in tf.data.TFRecordDataset([example_path]).map(decode_fn):
  print("x = {x:.4f},  y = {y:.4f}".format(**batch))
x = 0.5488,  y = 0.7152
x = 0.6028,  y = 0.5449
x = 0.4237,  y = 0.6459
x = 0.4376,  y = 0.8918

This class implements __enter__ and __exit__, and can be used in with blocks like a normal file. (See the usage example above.)

Methods

close

View source

close()

Close the file.

flush

View source

flush()

Flush the file.

write

View source

write(
    record
)

Write a string record to the file.

__enter__

__enter__()

enter(self: object) -> object

__exit__

__exit__()

exit(self: tensorflow.python._pywrap_record_io.RecordWriter, *args) -> None