util.py 文件源码

def read_examples(input_files, batch_size, shuffle, num_epochs=None):
  """Creates readers and queues for reading example protos."""
  files = []
  for e in input_files:
    for path in e.split(','):
      files.extend(file_io.get_matching_files(path))
  thread_count = multiprocessing.cpu_count()

  # The minimum number of instances in a queue from which examples are drawn
  # randomly. The larger this number, the more randomness at the expense of
  # higher memory requirements.
  min_after_dequeue = 1000

  # When batching data, the queue's capacity will be larger than the batch_size
  # by some factor. The recommended formula is (num_threads + a small safety
  # margin). For now, we use a single thread for reading, so this can be small.
  queue_size_multiplier = thread_count + 3

  # Convert num_epochs == 0 -> num_epochs is None, if necessary
  num_epochs = num_epochs or None

  # Build a queue of the filenames to be read.
  filename_queue = tf.train.string_input_producer(files, num_epochs, shuffle)

  example_id, encoded_example = tf.TextLineReader().read_up_to(
      filename_queue, batch_size)

  if shuffle:
    capacity = min_after_dequeue + queue_size_multiplier * batch_size
    return tf.train.shuffle_batch(
        [example_id, encoded_example],
        batch_size,
        capacity,
        min_after_dequeue,
        enqueue_many=True,
        num_threads=thread_count)

  else:
    capacity = queue_size_multiplier * batch_size
    return tf.train.batch(
        [example_id, encoded_example],
        batch_size,
        capacity=capacity,
        enqueue_many=True,
        num_threads=thread_count)


# ==============================================================================
# Building the TF learn estimators
# ==============================================================================