正则表达式环顾功能，中间有不相关的文本
我的文本应该包含tip然后top，此外，如果tap位于tip和top之间（按这个顺序，即tip...tap...top），那么tip和tap之间不能有其他顶部（按这个顺序，即tip ...顶部...点击...顶部是禁止的）。
一些示例
1. "tip tip top tip tip" TRUE
2. "top tip tup tip tap top" TRUE
3. "tip top tap tap top" FALSE
4. "tip tup top tap tap top" FALSE
5. "tip top tap tap tip" TRUE
我尝试过使用环视的
condition = (tip.*top) & (tip(?!.*top).*tap.*top)
str_detect("mytext", condition)
，例如，但它不起作用。
这是一个工作示例：
mytext = c("tip tip top tip tip" , "top tip tup tip tap top" ,
"tip top tap tap top" , "tip tup top tap tap top" , "tip top tap tap tip" )
condition = "(tip.*top) & (tip(?!.*top).*tap.*top)"
str_detect(mytext, condition)
它给出的
[1] FALSE FALSE FALSE FALSE FALSE
不是 TTFFT
My text should contain tip then top, Additionally, if tap is between tip and top (in that order, ie tip...tap...top), then no other top can be between tip and tap (in that order ie tip...top...tap...top is forbidden).
Some examples
1. "tip tip top tip tip" TRUE
2. "top tip tup tip tap top" TRUE
3. "tip top tap tap top" FALSE
4. "tip tup top tap tap top" FALSE
5. "tip top tap tap tip" TRUE
I have tried using lookarounds, eg
condition = (tip.*top) & (tip(?!.*top).*tap.*top)
str_detect("mytext", condition)
but it doesnt work.
Here is a working example:
mytext = c("tip tip top tip tip" , "top tip tup tip tap top" ,
"tip top tap tap top" , "tip tup top tap tap top" , "tip top tap tap tip" )
condition = "(tip.*top) & (tip(?!.*top).*tap.*top)"
str_detect(mytext, condition)
which gives
[1] FALSE FALSE FALSE FALSE FALSE
rather than T T F F T
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如果我们这样做怎么办：
What if we do this:
@KevinDialdestoro 给出了我会使用的解决方案，但如果您真的希望将所有内容都包含在一个正则表达式中，这里是将他的解决方案翻译成正则表达式语言：
(?=...)部分是“非消耗性” Lookahead”，并且(?!...)部分是否定。编辑添加：我的第一篇文章写错了。我认为现在已经解决了，但这就是为什么凯文的解决方案更好：它显然是正确的。
@KevinDialdestoro gave the solution I would use, but if you really want it all in one regexp, here's his solution translated into regex language:
The
(?=...)part is a "non-consuming lookahead", and the(?!...)part is a negation.EDITED TO ADD: My first posting got it wrong. I think it's fixed now, but that's why Kevin's solution is better: it's obviously correct.