用于捕获具有特定模式的日期的正则表达式

Question

我正在尝试从多个 pdf 文件中提取数据。有一个与日期相关的数据点，其中日期之前的字符串在某些 pdf 中有所不同。我检查了各个 regex 语句是否有效，但是，当我尝试将 regex 语句组合到我的 for 循环中的一个语句时，我没有提取日期。这是我尝试匹配的字符串以及我的代码，用于在 'DATE OF BIRTHDAY':

之后提取日期信息的各个正则表达式语句

DATE OF BIRTHDAY\n01/11/2011
date_of_birthday1 = re.search('(?<=DATE OF BIRTHDAY \n)(.*)', img).groups()

DATE OF BIRTHDAY\n\n02/14/2015
date_of_birthday2 = re.search('(?<=DATE OF BIRTHDAY \n\n)(.*)', img).groups()

DATE OF BIRTHDAY GIRL \n\ni : Pll i ii\ni \n\nPll 05/07/2018
date_of_birthday3 = re.search('(?<=DATE OF BIRTHDAY GIRL \n\ni : Pll i ii\ni \n\nPll)(.*)', img).groups()

我正在尝试将这些正则表达式语句组合成一个 or 语句，以便我可以在 for 循环中使用它们，如下所示：

date_of_birthdays = re.search('(?<=DATE OF BIRTHDAY\n\n)(.*)|(?<=DATE OF BIRTHDAY\n)(.*)|(?<=DATE OF BIRTHDAY GIRL \n\ni : Pll i ii\ni \n\nPll)(.*)', img).groups

我的预期输出是

df['Birthdays'] = date_of_birthdays

看起来像这样：

df = pd.DataFrame({"Birthdays": ['01/11/2011', '02/14/2015', '05/07/2018']})
df

但是，我无法提取任何日期信息。想一想我在这里做错了什么？

Answer 1

这个有效

>>> import re
>>> re.findall(
...  r"(?:DATE[ ]OF[ ]BIRTHDAY)(?:\n(?:\n)?|[ ]GIRL[ ]\n\ni[ ]:[ ]Pll[ ]i[ ]ii\ni[ ]\n\nPll[ ])?(.*)",
...  (
...  r'DATE OF BIRTHDAY\n01/11/2011' + "\n"
...  r'DATE OF BIRTHDAY\n\n02/14/2015' + "\n"
...  r'DATE OF BIRTHDAY GIRL \n\ni : Pll i ii\ni \n\nPll 05/07/2018' + "\n"
...  ))
['01/11/2011', '02/14/2015', '05/07/2018']
>>>

正则表达式扩展

 (?: DATE [ ] OF [ ] BIRTHDAY )

 (?:
      \ n 
      (?: \ n )?
   |  [ ] GIRL [ ] \ n \ ni [ ] : [ ] Pll [ ] i [ ] ii \ n i [ ] \ n \ n Pll [ ] 
 )?
 ( .* )                        # (1)

只是公平警告，表达式带有后向断言
在这两个交替中提出问题：

   (?<= DATE [ ] OF [ ] BIRTHDAY \ n \ n )
   ( .* )                        # (1)
|  (?<= DATE [ ] OF [ ] BIRTHDAY \ n )
   ( .* )                        # (2)

很难想象，所以我就直接说出来，
捕获组1（第一个交替）永远不会匹配！！

原因是总是先检查向后较短的距离。
由于 .* 给了它一种匹配方式，较短的一个 \n
文字总是首先匹配。

您可以通过添加 (?!\n) 来强制它不匹配来解决这个问题

   (?<= DATE [ ] OF [ ] BIRTHDAY \ n \ n )
   ( .* )                        # (1)
|  (?<= DATE [ ] OF [ ] BIRTHDAY \ n )
   (?! \ n )
   ( .* )                        # (2)

好吧，这太麻烦了，下面是
的一些基准正在考虑的方法（这并不是真正理想的方法）

Regex1:   (?:DATE[ ]OF[ ]BIRTHDAY)(?:\n(?:\n)?|[ ]GIRL[ ]\n\ni[ ]:[ ]Pll[ ]i[ ]ii\ni[ ]\n\nPll[ ])?(.*)
Options:  < none >
Completed iterations:   50  /  50     ( x 1000 )
Matches found per iteration:   3
Elapsed Time:    0.29 s,   294.80 ms,   294801 µs
Matches per sec:   508,817


Regex2:   (?:(?<=DATE[ ]OF[ ]BIRTHDAY\n\n)|(?<=DATE[ ]OF[ ]BIRTHDAY\n)(?!\n)|(?<=DATE[ ]OF[ ]BIRTHDAY[ ]GIRL[ ]\n\ni[ ]:[ ]Pll[ ]i[ ]ii\ni[ ]\n\nPll[ ]))(.*)
Options:  < none >
Completed iterations:   50  /  50     ( x 1000 )
Matches found per iteration:   3
Elapsed Time:    2.27 s,   2268.42 ms,   2268417 µs
Matches per sec:   66,125


Regex3:   (?<=DATE[ ]OF[ ]BIRTHDAY\n\n)(.*)|(?<=DATE[ ]OF[ ]BIRTHDAY\n)(?!\n)(.*)|(?<=DATE[ ]OF[ ]BIRTHDAY[ ]GIRL[ ]\n\ni[ ]:[ ]Pll[ ]i[ ]ii\ni[ ]\n\nPll[ ])(.*)
Options:  < none >
Completed iterations:   50  /  50     ( x 1000 )
Matches found per iteration:   3
Elapsed Time:    2.76 s,   2760.81 ms,   2760809 µs
Matches per sec:   54,331

用于捕获具有特定模式的日期的正则表达式

RegEx for capturing dates with specific pattern

python

regex

regex-group

regex-greedy

regex-lookarounds