拆分字符串和获取所有单词的Python正则表达式不起作用

问题描述

我正在尝试使用regular expression与python一起使用split字符串，并获取所有匹配的文字。

RE：w+(.?w+)*

此需要仅捕获[a-zA-Z0-9_]类内容。

Here is example

但是，当我尝试匹配并获取字符串中的所有内容时，它没有返回正确的结果。

代码段：

>>> import re
>>> from pprint import pprint
>>> pattern = r"w+(.?w+)*"
>>> string = """this is some test string and there are some digits as well that need to be captured as well like 1234567890 and 321 etc. But it should also select _ as well. I'm pretty sure that that RE does exactly the same.
... Oh wait, it also need to filter out the symbols like !@#$%^&*()-+=[]{}.,;:'"`| (`.`)/
... 
... I guess that's it."""
>>> pprint(re.findall(r"w+(.?w+)*", string))
[' etc', ' well', ' same', ' wait', ' like', ' it']

它只返回部分单词，但实际上它应该返回所有单词、数字和下划线[如链接示例中]。

python版本：Python 3.6.2(默认，2017-07 17，16：44：45)

谢谢。

---

解决方案

您需要使用非捕获组(请参阅here原因)并转义点(请参阅here哪些字符应该在正则表达式中转义)：

>>> import re
>>> from pprint import pprint
>>> pattern = r"w+(?:.?w+)*"
>>> string = """this is some test string and there are some digits as well that need to be captured as well like 1234567890 and 321 etc. But it should also select _ as well. I'm pretty sure that that RE does exactly the same.
... Oh wait, it also need to filter out the symbols like !@#$%^&*()-+=[]{}.,;:'"`| (`.`)/
... 
... I guess that's it."""
>>> pprint(re.findall(pattern, string, re.A))
['this', 'is', 'some', 'test', 'string', 'and', 'there', 'are', 'some', 'digits', 'as', 'well', 'that', 'need', 'to', 'be', 'captured', 'as', 'well', 'like', '1234567890', 'and', '321', 'etc', 'But', 'it', 'should', 'also', 'select', '_', 'as', 'well', 'I', 'm', 'pretty', 'sure', 'that', 'that', 'RE', 'does', 'exactly', 'the', 'same', 'Oh', 'wait', 'it', 'also', 'need', 'to', 'filter', 'out', 'the', 'symbols', 'like', 'I', 'guess', 'that', 's', 'it']

此外，若要仅匹配ASCII字母、数字和_，您必须传递re.A标志。

请参阅Python demo。