examples/legacy/seq2seq/rouge_cli.py/calculate_rouge_path
def calculate_rouge_path(pred_path, tgt_path, save_path=None, **kwargs):
    """Kwargs will be passed to calculate_rouge"""
    pred_lns = [x.strip() for x in open(pred_path).readlines()]
    tgt_lns = [x.strip() for x in open(tgt_path).readlines()][: len(pred_lns)]
    metrics = calculate_rouge(pred_lns, tgt_lns, **kwargs)
    if save_path is not None:
        save_json(metrics, save_path, indent=None)
    return metrics  # these print nicely