def _save_sorted_results(self, run_stats, scores, image_count, filename):
    """Saves sorted (by score) results of the evaluation.

    Args:
      run_stats: dictionary with runtime statistics for submissions,
        can be generated by WorkPiecesBase.compute_work_statistics
      scores: dictionary mapping submission ids to scores
      image_count: dictionary with number of images processed by submission
      filename: output filename
    """
    with open(filename, 'w') as f:
      writer = csv.writer(f)
      writer.writerow(['SubmissionID', 'ExternalTeamId', 'Score',
                       'MedianTime', 'ImageCount'])

      def get_second(x):
        """Returns second entry of a list/tuple"""
        return x[1]
      for s_id, score in sorted(iteritems(scores),
                                key=get_second, reverse=True):
        external_id = self.submissions.get_external_id(s_id)
        stat = run_stats.get(
            s_id, collections.defaultdict(lambda: float('NaN')))
        writer.writerow([s_id, external_id, score,
                         stat['median_eval_time'],
                         image_count[s_id]])
Saves sorted (by score) results of the evaluation.

    Args:
      run_stats: dictionary with runtime statistics for submissions,
        can be generated by WorkPiecesBase.compute_work_statistics
      scores: dictionary mapping submission ids to scores
      image_count: dictionary with number of images processed by submission
      filename: output filename