正则表达式用于多行字符串？

Question

我有以下输入：

str = """

    Q: What is a good way of achieving this?

    A: I am not sure. Try the following:

    1. Take this first step. Execute everything.

    2. Then, do the second step

    3. And finally, do the last one



    Q: What is another way of achieving this?

    A: I am not sure. Try the following alternatives:

    1. Take this first step from before. Execute everything.

    2. Then, don't do the second step

    3. Do the last one and then execute the above step

"""

我想在输入中捕获QA对，但是我无法获得良好的正则表达式来执行此操作。 我管理以下内容：

(?ms)^[\s#\-\*]*(?:Q)\s*:\s*(\S.*?\?)[\s#\-\*]+(?:A)\s*:\s*(\S.*)$

但是，我能够捕获输入，如下所示：

('Q', 'What is a good way of achieving this?')
('A', "I am not sure. Try the following:\n    1. Take this first step. Execute everything.\n    2. Then, do the second step\n    3. And finally, do the last one\n\n    Q: What is another way of achieving this?\n    A: I am not sure. Try the following alternatives:\n    1. Take this first step from before. Execute everything.\n    2. Then, don't do the second step\n    3. Do the last one and then execute the above step\n")

注意第二对质量检查对是如何被第一对捕获的。 如果我使用贪婪? 在答案正则表达式的末尾，它不捕获枚举。 关于如何解决这个问题有什么建议吗？

Answer 1

解决问题的一种惰性方法，但不是最好的方法，是用“ Q：”将字符串炸开，然后用简单的/Q:(.+)A:(.+)/msU（通常为正则表达式）解析这些部分。 。

Answer 2

只是使用它对我来说很好。 只需要修剪一点空白。

(?s)(Q):((?:(?!A:).)*)(A):((?:(?!Q:).)*)

使用示例：

>>> import re
>>> str = """
...
...     Q: What is a good way of achieving this?
...
...     A: I am not sure. Try the following:
...
...     1. Take this first step. Execute everything.
...
...     2. Then, do the second step
...
...     3. And finally, do the last one  ...      ...   ...
...     Q: What is another way of achieving this?
...
...     A: I am not sure. Try the following alternatives:
...
...     1. Take this first step from before. Execute everything.
...
...     2. Then, don't do the second step
...
...     3. Do the last one and then execute the above step
...
... """
>>> regex = r"(?s)(Q):((?:(?!A:).)*)(A):((?:(?!Q:).)*)"
>>> match = re.findall(regex, str)
>>> map(lambda x: [part.strip().replace('\n', '') for part in x], match)
[['Q', 'What is a good way of achieving this?', 'A', 'I am not sure. Try the following:    1. Take this first step. Execute everything.    2. Then, do the second step    3. And finally, do the last one'], ['Q', 'What is another way of achieving this?', 'A', "I am not sure. Try the following alternatives:    1. Take this first step from before. Execute everything.    2. Then, don't do the second step    3. Do the last one and then execute the above step"]]

甚至添加了一点小东西来帮助您清理那里的空白。

Answer 3

我编写大型正则表达式还不够聪明，所以这是我的非正则表达式解决方案-

>>> str = """

    Q: What is a good way of achieving this?

    A: I am not sure. Try the following:

    1. Take this first step. Execute everything.

    2. Then, do the second step

    3. And finally, do the last one



    Q: What is another way of achieving this?

    A: I am not sure. Try the following alternatives:

    1. Take this first step from before. Execute everything.

    2. Then, don't do the second step

    3. Do the last one and then execute the above step

"""
>>> qas = str.strip().split('Q:')
>>> clean_qas = map(lambda x: x.strip().split('A:'), filter(None, qas))
>>> print clean_qas
[['What is a good way of achieving this?\n\n    ', ' I am not sure. Try the following:\n\n    1. Take this first step. Execute everything.\n\n    2. Then, d
o the second step\n\n    3. And finally, do the last one'], ['What is another way of achieving this?\n\n    ', " I am not sure. Try the following alternativ
es:\n\n    1. Take this first step from before. Execute everything.\n\n    2. Then, don't do the second step\n\n    3. Do the last one and then execute the
above step"]]

不过，您应该清理空格。 或者，您可以按照Puciek所说的去做。

纯娱乐 -

>>> clean_qas = map(lambda x: map(lambda s: s.strip(), x.strip().split('A:')), filter(None, qas))
>>> print clean_qas
[['What is a good way of achieving this?', 'I am not sure. Try the following:\n\n    1. Take this first step. Execute everything.\n\n    2. Then, do the sec
ond step\n\n    3. And finally, do the last one'], ['What is another way of achieving this?', "I am not sure. Try the following alternatives:\n\n    1. Take
 this first step from before. Execute everything.\n\n    2. Then, don't do the second step\n\n    3. Do the last one and then execute the above step"]]

虽然看起来很丑。

Answer 4

稍微修改您的原始解决方案：

(?ms)^[\s#\-\*]*(?:Q)\s*:\s+(\S[^\n\r]*\?)[\s#\-\*]+(?:A)\s*:\s+(\S.*?)\s*(?=$|Q\s*:\s+)

• 问题和答案必须在:之后至少有一个空格。
• 与其以非贪婪的方式匹配问题（不允许一个问题中包含多个? ），还不应该在问题中使用换行符。
• 相反，匹配结束串的，非贪婪地匹配， 直到在比赛之后的字符串的结尾，或者它接着另一个问题。

使用re.findall获取所有问题/答案匹配。