如何使用python和multiindex执行v查找

import pandas as pd

data = {'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8],
        'C': [9, 10, 11, 12]}
index = pd.MultiIndex.from_tuples([('Group 1', 'Subgroup 1'), ('Group 1', 'Subgroup 2'),
                                  ('Group 2', 'Subgroup 1'), ('Group 2', 'Subgroup 2')])
df = pd.DataFrame(data, index=index)

result = df.loc[('Group 1', 'Subgroup 1'), 'A']

result = df.loc[[('Group 1', 'Subgroup 1'), ('Group 2', 'Subgroup 2')], 'A']

result = df.loc[('Group 1', slice(None)), 'A']

result = df.loc[df['A'] > 2, 'B']