什么是正则表达式？

Question

我正在使用 Nltk 的 punkt 分词器将段落分词成句子，但在某些情况下，例如下面的示例，分词器无法识别句子，因为句点后跟数字。我想使用正则表达式识别这些场景并将'.1,7,9' 替换为'. 1,7,9'，即在引用和句点之间添加空格。

Ex1.  `This is a random sentence.1,7,9 This is a sentence followed by it.`
Ex2. I love football.1,7,24`I also like cricket.

Ex3. ESD for undifferentiated  cancers.[1][7]`Cancers can be treatable.

预期输出：

EX1. This is a random sentence.
     1,7,9 This is a sentence followed by it.
Ex2. I love football.
     ESD for undifferentiated  cancers.1,7
Ex3. ESD for undifferentiated  cancers.1,7
     [1][7]`Cancers can be treatable.

谢谢。

Answer 1

下面的正则表达式将用. + \n替换所有非空格字符后面的点

>>> import re
>>> s = "Ex1.  This is a random sentence.1,7,9 This is a sentence followed by it."
>>> print(re.sub(r'\.(\S)', r'.\n\1', s))
Ex1.  This is a random sentence.
1,7,9 This is a sentence followed by it.

DEMO

Answer 2

在附加的整数列表是引用的情况下，将字符返回放在整数列表之后可能会很有用：

>>> import re
>>> s = "Ex1.  This is a random sentence.1,7,9 This is a sentence followed by it."
>>> print(re.sub(r'(\.\S+\s)', r'\1\n', s))
Ex1.  This is a random sentence.1,7,9 
This is a sentence followed by it.