在Python Pandas中使用regex进行数据提取

看起来您想要提取这样的日期:第一个数字是month，然后是day，然后是以1或2开头的year，然后包含任何数字，然后可以 Select 后跟两个数字.

您可以使用

df.str.extract(r'\b(?:(0?[1-9]|1[0-2])[/-])?(?:(0?[1-9]|[12]\d|3[01])[/-])?((?:[12]\d)?\d{2})\b', expand=False)

见the regex demo.

More details个

• \b-一个词的边界
• (?:(0?[1-9]|[12]\d|3[01])[/-])? - an optional sequence of
  • (0?[1-9]|[12]\d|3[01])-组1:可选的0，然后是非零数字，或者1或2和任意数字，或者3，然后是0或1
  • [/-]-A /或-
• (?:(0?[1-9]|1[0-2])[/-])? - an optional sequence of
  • (0?[1-9]|1[0-2])-组2:可选的0，然后是非零数字，或者1，然后是0、1或2
  • [/-]-A /或-
• ((?:[12]\d)?\d{2})-组3:1或2的可选序列，然后是任意一个数字，然后是两个数字
• \b-一个词的边界

Pandas代码:

import pandas as pd
df = pd.DataFrame({'text':['1/1994 Primary Care Doctor:\n', 'sshe plans to move as of 7/8/71 In-Home Services: None\n', 'Reports MRI of brain done 12/2004 at Gravette Medical Center was WNLPrior EEG:\n']})
df[['month','day','year']] = df['text'].str.extract(r'\b(?:(0?[1-9]|1[0-2])[/-])?(?:(0?[1-9]|[12]\d|3[01])[/-])?((?:[12]\d)?\d{2})\b', expand=False)
df
                                                text month  day  year
0                      1/1994 Primary Care Doctor:\n     1  NaN  1994
1  sshe plans to move as of 7/8/71 In-Home Servic...     7    8    71
2  Reports MRI of brain done 12/2004 at Gravette ...    12  NaN  2004