4级嵌套字典转换为pandas dataframe python

import pandas as pd

def flatten_dict(d, parent_key='', sep='_'):
    items = []
    for k, v in d.items():
        new_key = parent_key + sep + k if parent_key else k
        if isinstance(v, dict):
            items.extend(flatten_dict(v, new_key, sep=sep).items())
        else:
            items.append((new_key, v))
    return dict(items)

def nested_dict_to_dataframe(nested_dict):
    flattened_dict = flatten_dict(nested_dict)
    df = pd.DataFrame.from_dict(flattened_dict, orient='index').T
    return df

nested_dict = {
    'A': {
        'a': {
            '1': 10,
            '2': 20
        },
        'b': {
            '1': 30,
            '2': 40
        }
    },
    'B': {
        'a': {
            '1': 50,
            '2': 60
        },
        'b': {
            '1': 70,
            '2': 80
        }
    }
}

df = nested_dict_to_dataframe(nested_dict)
print(df)

   A_a_1  A_a_2  A_b_1  A_b_2  B_a_1  B_a_2  B_b_1  B_b_2
0     10     20     30     40     50     60     70     80