从dataframe中的行中复制匹配模式的字符串，并放入新dataframe中的新列中

import pandas as pd
import re

new_df = pd.DataFrame()

for index, row in df.iterrows():
    # 提取匹配模式的字符串
    match = re.search(pattern, row['column_name'])
    if match:
        matched_string = match.group()
    else:
        matched_string = ""
    
    # 将匹配的字符串添加到新dataframe的新列中
    new_df.at[index, 'new_column'] = matched_string