基于特定 substring 的 python 正则表达式提取

Question

I have a dataframe containing sentences like the following but with more rows:

data= {"text":["see you in five minutes.", "she is my friend.", "she goes to school in five minutes."]}

I would like to extract the sentences containing 'five minutes' in the manner presented below:

desired output:

     first part              desired part     
0    see you in              five minutes.
1    NaN                     NaN
2    she goes to school in   five minutes.

I am using the following code but it returns NaN:

data.text.str.extract(r"(?i)(?P<before>.*)\s(?P<minutes>(?=five minutes\s))\w+ \w+")    

Answer 1

You require a whitespace when there's none:

(?i)(?P<before>.*)\s(?P<minutes>(?=five minutes\s))\w+ \w+
#                                              ^^^

Either use the star quantifier (zero or more time) or rethink your expression. The following works:

import pandas as pd

data= {"text":["see you in five minutes.", "she is my friend.", "she goes to school in five minutes."]}

df = pd.DataFrame(data)
df2 = df.text.str.extract(r"(?i)(?P<before>.*?)(?=five minutes)(?P<after>.*)")
print(df2)

And yields

                   before          after
0             see you in   five minutes.
1                     NaN            NaN
2  she goes to school in   five minutes.