Read and sort lines from the file sorted by decreasing length.

  Args:
    filename: String name of file to read inputs from.
  Returns:
    Sorted list of inputs, and dictionary mapping original index->sorted index
    of each element.

def _get_sorted_inputs(filename):
  """Read and sort lines from the file sorted by decreasing length.

  Args:
    filename: String name of file to read inputs from.
  Returns:
    Sorted list of inputs, and dictionary mapping original index->sorted index
    of each element.
  """
  with tf.gfile.Open(filename) as f:
    records = f.read().split("\n")
    inputs = [record.strip() for record in records]
    if not inputs[-1]:
      inputs.pop()

  input_lens = [(i, len(line.split())) for i, line in enumerate(inputs)]
  sorted_input_lens = sorted(input_lens, key=lambda x: x[1], reverse=True)

  sorted_inputs = []
  sorted_keys = {}
  for i, (index, _) in enumerate(sorted_input_lens):
    sorted_inputs.append(inputs[index])
    sorted_keys[index] = i
  return sorted_inputs, sorted_keys