如何根据字典键从嵌套的字典中创建多个新的数据框列

import pandas as pd

nested_dict = {
    'key1': {'subkey1': 1, 'subkey2': 2},
    'key2': {'subkey1': 3, 'subkey2': 4}
}

df = pd.DataFrame.from_dict(nested_dict, orient='index')

df['new_column1'] = df.apply(lambda x: x['subkey1'], axis=1)
df['new_column2'] = df.apply(lambda x: x['subkey2'], axis=1)

import pandas as pd

nested_dict = {
    'key1': {'subkey1': 1, 'subkey2': 2},
    'key2': {'subkey1': 3, 'subkey2': 4}
}

df = pd.DataFrame.from_dict(nested_dict, orient='index')

df['new_column1'] = df.apply(lambda x: x['subkey1'], axis=1)
df['new_column2'] = df.apply(lambda x: x['subkey2'], axis=1)

print(df)

      subkey1  subkey2  new_column1  new_column2
key1        1        2            1            2
key2        3        4            3            4