不依赖Pandas，如何快速分组二维列表？

def group_name_fun(lst):    last = ''    arr = []    for ii in range(len(lst)):        if not lst[ii][0] == last:            arr.append(ii)            last = lst[ii][0]    arr.append(len(lst))    lst = [lst[arr[ii - 1]:arr[ii]] for ii in range(1, len(arr))]    return lst

import itertoolsdef group_large_array(data):    grouped_data = {}    for key, group in itertools.groupby(data, lambda x: x[0]):        grouped_data[key] = [item[1] for item in group]    # 转换为列表形式    result = [grouped_data[key] for key in grouped_data]    return result