def get_div_winners(df_sim):
    """Calculate division winners with summarised simulation data

  :param df_sim: data frame with simulated scores summarised by iteration
  :return: data frame with division winners per iteration
  """
    return df_sim.sort_values(by=['tot_wins', 'tot_pts'], ascending=[False,
        False]).groupby(['iteration', 'divisionId']).head(1).sort_values(by
        =['divisionId', 'iteration']).reset_index(drop=True)
