merge.py 文件源码

def _sort_labels(uniques, left, right):
    if not isinstance(uniques, np.ndarray):
        # tuplesafe
        uniques = Index(uniques).values

    sorter = uniques.argsort()

    reverse_indexer = np.empty(len(sorter), dtype=np.int64)
    reverse_indexer.put(sorter, np.arange(len(sorter)))

    new_left = reverse_indexer.take(com._ensure_platform_int(left))
    np.putmask(new_left, left == -1, -1)

    new_right = reverse_indexer.take(com._ensure_platform_int(right))
    np.putmask(new_right, right == -1, -1)

    return new_left, new_right