Question

我在python中使用RE表达式并试图按句点和感叹号分割一段文本。但是当我拆分它时，我在结果中得到“无”

a = "This is my text...I want it to split by periods. I also want it to split \
by exclamation marks! Is that so much to ask?"

这是我的代码：

re.split('((?<=\w)\.(?!\..))|(!)',a)

请注意，我有这个（？＆lt; = \ w）。（？！..），因为我希望它避免使用省略号。不过，上面的代码吐出来了：

['This is my text...I want it to split by periods', '.', None, ' \
I also want it to split by exclamation marks', None, '!', \
' Is that so much to ask?']

正如您所看到的，在句号或感叹号所在的位置，它在我的列表中添加了一个特殊的“无”。为什么这样，我该如何摆脱它？

Answer 1

尝试以下方法：

re.split(r'((?<=\w)\.(?!\..)|!)', a)

您获得None，因为您有两个捕获组，并且所有组都包含在re.split()结果中。

因此，只要您匹配.第二个捕获组None，只要您匹配!，第一个捕获组就是None。

结果如下：

['This is my text...I want it to split by periods',
 '.',
 ' I also want it to split by exclamation marks',
 '!',
 ' Is that so much to ask?']

如果您不想在结果中加入'.'和'!'，只需删除围绕整个表达式的括号：r'(?<=\w)\.(?!\..)|!'

Answer 2

这是一个更简单的表达式（任何句号未跟随或之前的句点），外部捕获组围绕整个或|子句，以避免None，而不仅仅是第一部分：

re.split(r'((?<!\.)\.(?!\.)|!)', a)

# Result:
# ['This is my text...I want it to split by periods', 
#  '.', 
#  ' I also want it to split by exclamation marks', 
#  '!', 
#  ' Is that so much to ask?']

Answer 3

它正在发生，因为在每个感叹号之后都有一个空格字符，在此处返回None。

您可以使用过滤器删除这些None。

>>> import re
>>> a = "This is my text...I want it to split by periods. I also want it to split \
by exclamation marks! Is that so much to ask?"

>>> filter(lambda x:x!=None, re.split('((?<=\w)\.(?!\..))|(!)',a))

['This is my text...I want it to split by periods', '.', ' I also want it to split by exclamation marks', '!', ' Is that so much to ask?']

RE拆分多个参数| （或）返回none python

3 个答案: