python - 如何在“否”，“否”和“从不”之后的否定单词中添加标签

如何将标记NEG_添加到not、no和never后面的所有单词中，直到字符串中的下一个标点符号（用于情绪分析）？我认为可以使用正则表达式，但我不确定如何使用。
输入：It was never going to work, he thought. He did not play so well, so he had to practice some more.
期望输出：It was never NEG_going NEG_to NEG_work, he thought. He did not NEG_play NEG_so NEG_well, so he had to practice some more.
知道怎么解决这个问题吗？

最佳答案

为了弥补Python的regex引擎缺少一些Perl功能，可以在re函数中使用lambda表达式来创建动态替换：

import re
string = "It was never going to work, he thought. He did not play so well, so he had to practice some more. Not foobar !"
transformed = re.sub(r'\b(?:not|never|no)\b[\w\s]+[^\w\s]',
       lambda match: re.sub(r'(\s+)(\w+)', r'\1NEG_\2', match.group(0)),
       string,
       flags=re.IGNORECASE)

将打印（demo here）

It was never NEG_going NEG_to NEG_work, he thought. He did not NEG_play NEG_so NEG_well, so he had to practice some more. Not NEG_foobar !

解释
第一步是选择你感兴趣的部分。这已经结束了

\b(?:not|never|no)\b[\w\s]+[^\w\s]

你的否定关键字（re.sub是一个单词边界，\b是一个非捕获组），后面是alpahnum和空格（(?:...)是\w，[0-9a-zA-Z_]是所有类型的空白），直到既不是字母也不是空格（用作标点符号）。
注意这里的标点符号是必需的，但是您也可以安全地删除\s来匹配字符串的结尾。
现在您要处理的是[^\w\s]类型的字符串。只需选择前面有空格的单词

(\s+)(\w+)

换成你想要的

\1NEG_\2