python - pandas:如何为列中的每个子字符串复制一个值

Question

我有一个 pandas 数据框，如下所示，

import pandas as pd

df = pd.DataFrame({'text': ['set an alarm for [time : two hours from now]','wake me up at [time : nine am] on [date : friday]','check email from [person : john]']})
print(df)

原始数据框

                                                text
0       set an alarm for [time : two hours from now]
1  wake me up at [time : nine am] on [date : friday]
2                   check email from [person : john]

如果列表中的值不止一个，我想为列表中的所有值重复列表和标签(日期、时间和人物)。所以所需的输出是，

期望的输出:

                                                new_text                                
0       set an alarm for [time : two] [time : hours] [time : from] [time : now]        
1  wake me up at [time : nine] [time : am] on [date : friday]  
2                   check email from [person : john]

到目前为止，我已尝试将列表与原始列分开，但不知道如何继续。

df['separated_list'] = df.text.str.split(r"\s(?![^[]*])|[|]").apply(lambda x: [y for y in x if '[' in y])

Answer 1

您可以使用带有自定义函数的正则表达式作为替换:

df['new_text'] = df.text.str.replace(
  r"\[([^\[\]]*?)\s*:\s*([^\[\]]*)\]",
  lambda m: ' '.join([f'[{m.group(1)} : {x}]'
                      for x in m.group(2).split()]), # new chunk for each word
  regex=True)

输出:

                                                text                                                                 new_text
0       set an alarm for [time : two hours from now]  set an alarm for [time : two] [time : hours] [time : from] [time : now]
1  wake me up at [time : nine am] on [date : friday]               wake me up at [time : nine] [time : am] on [date : friday]
2                   check email from [person : john]                                         check email from [person : john]

regex demo