查找所有出现的子字符串(包括重叠)? [英] Find all occurrences of a substring (including overlap)?

问题描述

好的，所以我找到了这个:如何找到所有出现的一个子串?

Okay, so I found this: How to find all occurrences of a substring?

也就是说，要获取列表中子字符串重叠出现的索引，您可以使用:

Which says, to get the indices overlapping occurances of substrings in a list, you can use:

[m.start() for m in re.finditer('(?=SUBSTRING)', 'STRING')]

哪个有效，但我的问题是要查找的字符串和子字符串都是由变量定义的.我对正则表达式的了解不够，不知道如何处理它 - 我可以让它与不重叠的子字符串一起工作，这只是:

Which works, but my problem is that both the string and the substring to look for are defined by variables. I don't know enough about regular expressions to know how to deal with it - I can get it to work with non-overlapping substrings, that's just:

[m.start() for m in re.finditer(p3, p1)]

因为有人问，所以我会继续说明.p1 和 p3 可以是任何字符串，但如果它们是，例如 p3 = "tryt" 和 p1 = "trytryt"，结果应该是 [0, 3].

Because someone asked, I'll go ahead and specfify. p1 and p3 could be any string, but if they were, for example p3 = "tryt" and p1 = "trytryt", the result should be [0, 3].

推荐答案

re.finditer 是简单的字符串.如果变量中有子字符串，只需将其格式化为正则表达式即可.像 '(?={0})'.format(p3) 这样的东西是一个开始.由于 各种符号在 RE 中确实具有特殊含义，您会想逃避他们.幸运的是 re 模块 包括 re.escape 正是为了满足这种需求.>

The arguments to re.finditer are simple strings. If you have the substring in a variable simply format it into the regular expression. Something like '(?={0})'.format(p3) is a start. Since various symbols do have special meaning in a RE you will want to escape them. Luckily the re module includes re.escape for just such a need.

[m.start() for m in re.finditer('(?={0})'.format(re.escape(p3)), p1)]

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