是否可以选择特定的正则表达式捕获组来在Pandas中创建列？

import pandas as pd

# 创建示例DataFrame
df = pd.DataFrame({'datetime': ['2022-01-01 12:34:56', '2022-02-03 09:08:07', '2022-03-05 18:30:45']})

# 使用正则表达式提取年份和月份
df['year'] = df['datetime'].str.extract(r'(\d{4})')
df['month'] = df['datetime'].str.extract(r'-(\d{2})-')

# 输出结果
print(df)

             datetime  year month
0  2022-01-01 12:34:56  2022    01
1  2022-02-03 09:08:07  2022    02
2  2022-03-05 18:30:45  2022    03