For a URL pattern such as this one:
/detail.php?a=BYGhs5w8e9o&b=234844617545&h=9827a
I would like Google Analytics to match only the URL's with the a and b parameters in it:
/orderdetail.php?a=BYGhs5w8e9o&b=234844617545
And thus strip out:
&h=9827a
The main goal is to be able to setup a goal in Google Analytics which covers only the a and b parameters and ignores the h parameter.
Is there an easy way to accomplish this without a negative lookahead?
Standard regular expressions do not need negative lookahead for this. Just do a match and replace. Searching for:
(/detail.php\?a=\w+&b=\w+)&h=\w+
and replacing with \1 works with the regular expressions in Notepad++ version 6.5.5. Google's regular expressions may be subtly different.
The above works by surrounding the wanted text with capturing braces and leaving the unwanted part outside. The ? needs escaping as un-escaped it means the previous item (ie the p) is optional. The \w sequence mean any "word" character so \w+ means a word.
Related
Within Splunk I have a number of field extractions for extracting values from uri stems. I have a few which match a specific pattern, I now want another regex which matches anything but these.
^/SiteName/[^/]*/(?<a_request_type>((?!Process)|(?!process)|(?!Assets)|(?!assets))[^/]+)
The regex above is what I have so far. I am expecting the negative lookaheads to prevent it from matching Process, process, assets or Assets. However it seems that the [^/]+ after these lookaheads can then go ahead and match these strings anyway. Resulting in this regex sometimes overriding the other regexes I wrote to accept these strings
What is the correct syntax for me to make the regex match any string, other than those specified in the negative lookaheads?
Thanks!
Negative lookaheads do not consume any of the string being searched. When you want multiple negative lookaheads, there is no need to separate them with | (OR). Try this:
^/SiteName/[^/]*/(?<a_request_type>((?![Pp]rocess)(?![Aa]ssets))[^/]+)
Note that I have combined your lookaheads ([Pp]rocess and [Aa]ssets) to make the regular expression more concise.
Live test.
I'm trying to detect occurrences of words italicized with *asterisks* around it. However I want to ensure it's not within a link. So it should find "text" in here is some *text* but not within http://google.com/hereissome*text*intheurl.
My first instinct was to use look aheads, but it doesn't seem to work if I use a URL regex such as John Gruber's:
(?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]))
And put it in a look ahead at the beginning of the pattern, followed by the rest of the pattern.
(?=URLPATTERN)\*[a-zA-Z\s]\*
So how would I do this?
You can use this alternation technique to match everything first on LHS that you want to discard. Then on RHS use captured group to match desired text.
https?:\/\/\S*|(\*\S+\*)
You can then use captured group #1 for your emphasized text.
RegEx Demo
The following regexp:
^(?!http://google.com/hereissome.*text.*intheurl).*
Matches everything but http://google.com/hereissome*text*intheurl. This is called negative lookahead. Some regexp libraries may not support it, python's does.
Here is a link to Mastering Lookahead and Lookbehind.
I am having an issue with trying to figure out how to insert some text after I perform a regex search. I know there is a replace function, but I am not looking for that option, just inserting. The text editor I am using is Notepad2, but I am willing to try this in other text editors.
Here is the example that I have.
TEST|Test2|Test3|Test4
This is what I am looking for
Test|Test2|PrefixTest3|Test4
Notice that I am trying to insert the the phrase "Prefix" after the 2nd pipe and leave everything else alone.
I can successfully query the result by using this regex:
^[^|]*\|[^|]*|
But then I do not know how I can retain everything prior and after the search point. Any ideas?
You could simply use \K inorder to discard the previously matched characters.
^[^|]*\|[^|]*\|\K
Then replace the match with the string prefix.
DEMO
You may easily do that in Notepad2 using the regex-based Replace feature.
Find: ^\([^|]*|[^|]*|\)
Replace: \1Prefix
Details:
^ - start of a line (Notepad2 never overflows line boundaries!)
\([^|]*|[^|]*|\) - Capturing group 1 matching a sequence of:
[^|]* - zero or more chars other than |
| - a literal (yes, no escaping is necessary, both escaped and unescaped | match a literal |) pipe symbol
[^|]*| - see above, gets to the second |.
The replacement contains a \1 backreference that inserts what was captured with the capturing group 1.
NOTE that Notepad2 regex engine is very limited. Here is what the Notepad2 documentation says:
Notepad2 supports only a limited subset of regular expressions, as provided by built-in engine of the Scintilla source code editing component. The advantage is that it has a very small footprint. There's currently no plans to integrate a more advanced regular expressions engine, but this may be an option for future development.
Note: Regular expression search is limited to single lines, only.
Also, you may refer to the inline comments inside Scintilla RESearch.cxx file describing the supported syntax. Bear in mind that the regex type used in the Notepad2 S&R tool is that of POSIX and not all of the described Scintilla regex features will work in the tool.
Note that Notepad2 does not seem to support alternation and limiting quantifiers (similar to Lua patterns), but \w matches Unicode letters together with ASCII ones. Sadly, I could not make ? quantifier work.
^([^|]*\|[^|]*\|)
Try this.Replace by $1prefix.See demo.Just capture the first group and then use it for replace.The first group can be accessed by $1.
http://regex101.com/r/pQ9bV3/11
I have a source file with literally hundreds of occurrences of strings flecha.jpg and flecha1.jpg, but I need to find occurrences of any other .jpg image (i.e. casa.jpg, moto.jpg, whatever)
I have tried using a regular expression with negative lookbehind, like this:
(?<!flecha|flecha1).jpg
but it doesn't work! Notepad++ simply says that it is an invalid regular expression.
I have tried the regex elsewhere and it works, here is an example so I guess it is a problem with NPP's handling of regexes or with the syntax of lookbehinds/lookaheads.
So how could I achieve the same regex result in NPP?
If useful, I am using Notepad++ version 6.3 Unicode
As an extra, if you are so kind, what would be the syntax to achieve the same thing but with optional numbers (in this case only '1') as a suffix of my string? (even if it doesn't work in NPP, just to know)...
I tried (?<!flecha[1]?).jpg but it doesn't work. It should work the same as the other regex, see here (RegExr)
Notepad++ seems to not have implemented variable-length look-behinds (this happens with some tools). A workaround is to use more than one fixed-length look-behind:
(?<!flecha)(?<!flecha1)\.jpg
As you can check, the matches are the same. But this works with npp.
Notice I escaped the ., since you are trying to match extensions, what you want is the literal .. The way you had, it was a wildcard - could be any character.
About the extra question, unfortunately, as we can't have variable-length look-behinds, it is not possible to have optional suffixes (numbers) without having multiple look-behinds.
Solving the problem of the variable-length-negative-lookbehind limitation in Notepad++
Given here are several strategies for working around this limitation in Notepad++ (or any regex engine with the same limitation)
Defining the problem
Notepad++ does not support the use of variable-length negative lookbehind assertions, and it would be nice to have some workarounds. Let's consider the example in the original question, but assume we want to avoid occurrences of files named flecha with any number of digits after flecha, and with any characters before flecha. In that case, a regex utilizing a variable-length negative lookbehind would look like (?<!flecha[0-9]*)\.jpg.
Strings we don't want to match in this example
flecha.jpg
flecha1.jpg
flecha00501275696.jpg
aflecha.jpg
img_flecha9.jpg
abcflecha556677.jpg
The Strategies
Inserting Temporary Markers
Begin by performing a find-and-replace on the instances that you want to avoid working with - in our case, instances of flecha[0-9]*\.jpg. Insert a special marker to form a pattern that doesn't appear anywhere else. For this example, we will insert an extra . before .jpg, assuming that ..jpg doesn't appear elsewhere. So we do:
Find: (flecha[0-9]*)(\.jpg)
Replace with: $1.$2
Now you can search your document for all the other .jpg filenames with a simple regex like \w+\.jpg or (?<!\.)\.jpg and do what you want with them. When you're done, do a final find-and-replace operation where you replace all instances of ..jpg with .jpg, to remove the temporary marker.
Using a negative lookahead assertion
A negative lookahead assertion can be used to make sure that you're not matching the undesired file names:
(?<!\S)(?!\S*flecha\d*\.jpg)\S+\.jpg
Breaking it down:
(?<!\S) ensures that your match begins at the start of a file name, and not in the middle, by asserting that your match is not preceded by a non-whitespace character.
(?!\S*flecha\d*\.jpg) ensures that whatever is matched does not contain the pattern we want to avoid
\S+\.jpg is what actually gets matched -- a string of non-whitespace characters followed by .jpg.
Using multiple fixed-length negative lookbehinds
This is a quick (but not-so-elegant) solution for situations where the pattern you don't want to match has a small number of possible lengths.
For example, if we know that flecha is only followed by up to three digits, our regex could be:
(?<!flecha)(?<!flecha[0-9])(?<!flecha[0-9][0-9])(?<!flecha[0-9][0-9][0-9])\.jpg
Are you aware that you're only matching (in the sense of consuming) the extension (.jpg)? I would think you wanted to match the whole filename, no? And that's much easier to do with a lookahead:
\b(?!flecha1?\b)\w+\.jpg
The first \b anchors the match to the beginning of the name (assuming it's really a filename we're looking at). Then (?!flecha1?\b) asserts that the name is not flecha or flecha1. Once that's done, the \w+ goes ahead and consumes the name. Then \.jpg grabs the extension to finish off the match.
I have the following sample expression that I'm passing to egrep over a word list:
^([a-z])lu([a-z])\2er$
I'd like to further stipulate that the content of \1 and \2 must be different, e.g. this would match "bluffer" but not "blubber". Is there a way to build this into the expression itself (so I can get my results right from egrep or something like it), or am I stuck doing this in some real language with regular expression support and manually checking that none of my groups are the same?
You could add the negative lookahead (?!\1) in front of the 2nd match group. The following regex:
([a-z])lu(?!\1)([a-z])\2er
matches "bluffer" but not "blubber". This only works properly if both the groups match the same amount of characters.
You need something more powerful. Regular expressions can't track state. Sed could probably do what you need.