def get_diagnostics(self):
        path_lens = [len(path['actions']) for path in self._epoch_paths]
        stats = OrderedDict([
            ('num steps total', self._num_steps_total),
            ('num paths total', self._num_paths_total),
        ])
        stats.update(create_stats_ordered_dict(
            "path length",
            path_lens,
            always_show_all_stats=True,
        ))
        return stats