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Regex: Select only the first instance of search results / first match

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  • V
    Vasile Caraus
    last edited by Sep 12, 2016, 12:48 PM

    I found on internet a more simple way

    Step1. Enable the . matches newline option

    Search
    <div class=“pagination”>(.*)\z
    Replace by:
    Anything $1

    1 Reply Last reply Reply Quote 0
    • G
      guy038
      last edited by Sep 13, 2016, 11:11 AM

      Hi, Vasile,

      Two points :

      • Firstly, Vasile, don’t be mistaken about what I wrote, at the end of my previous post ! I was just dreaming about it ! Of course, these options are NOT part of the present “Find/Replace” dialog. And they, probably, will NEVER be :-((

      I just wanted to point out that these additional options could help us, in some cases, to build more simple regexes !


      • Secondly, yes, you’re right : your regex is more elegant ! But it works ONLY IF there is ONE string <div class=“pagination”>, exactly, in your current file. And seemingly, you said :

      The problem is that this line is repeated 5 times in each html file

      But, indeed, it’s incredible how our brain is disposed to make simple things more complicated:-(( So, from your interesting regex, we can, still, simplify the previous regexes :


      • To change the contents of the FIRST line, ONLY, of the current file, containing the string <div class=“pagination”>, use :

      SEARCH : (?s)<div class=“pagination”>(.*)

      REPLACE : Anything else\1

      • To change the contents of the LAST line, ONLY, of the current file, containing the string <div class=“pagination”>, use :

      SEARCH : (?s).*\K<div class=“pagination”>(.*)

      REPLACE : Anything else\1


      I don’t think we’ll be able to get shorter regexes !!

      Notes :

      • As usual, the in-line modifier (?s) prevent us to mind about checking/unchecking the .matches newline option

      • In the second regex, we need to add, at the beginning, the form .*\K, in order to get the maximum range of characters till the last string <div class=“pagination”>, of the current file

      • The last part of the regex (.*) represents the remaining text, after the matched string <div class=“pagination”>, till the very end of file

      Cheers,

      guy038

      1 Reply Last reply Reply Quote 0
      • V
        Vasile Caraus
        last edited by Vasile Caraus Sep 13, 2016, 2:36 PM Sep 13, 2016, 2:35 PM

        hello guy, works wonderful. Thank you.

        But one more thing, I cannot get the solution. At the regex below, as you can see, first part I select all before a word. And part two select all after a word. Practicaly, I select a middle text from a file. Works beautiful. I use Replace All for more then 2000 files.

        (?s)((^.*)(DELETE_UNTIL_THIS_TEXT)|(DELETE_AFTER_THIS_TEXT)(.*$))

        Sometimes, the problem is when I have more instances at the last part. For exemple:

        text_1
        DELETE_UNTIL_THIS_TEXT (text_1)
        –my text–
        –my text–
        DELETE_AFTER_THIS_TEXT (text_2)
        text_2
        text_2
        text_2

        So as you can see at the last part, I have three (or much more) instances (occurences) of the same “text_2.”
        When I run regex, will delete all the instances text_2.

        So, I want to delete just the last instance of text_2 in the regex. I will right again, but it should be modify a little bit for the second part.

        (?s)((^.*)(text_1)|(text_2)(.*$))

        1 Reply Last reply Reply Quote 0
        • G
          guy038
          last edited by guy038 Sep 13, 2016, 5:56 PM Sep 13, 2016, 4:32 PM

          Hello Vasile,

          As you know, regexes force and help us to keep a rigorous attitude, as well as programming do ! So I, slightly, change your example text, in order to exactly see what you need !

          So, let’s suppose the example text, of 20 lines, below :

          Line 01
          Line 02
          Line 03 Text_1
          Line 04
          Line_05
          Text_1
          Line 07
          Line 08
          Line 09 Text_1
          Line_10
          Line_11
          Text_2 Line 12
          Line_13
          Line_14
          Text_2
          Line_16
          Line_17
          Text_2 Line_18
          Line_19
          Line_20
          

          Do you like to delete, in one go, :

          • All lines till the first occurrence of Text_1 ( so, lines 01,02 and 03 ) AND all lines from the first occurrence of Text_2 ( so, from lines 12 to 20 ) = case A

          • All lines till the first occurrence of Text_1 ( so, lines 01,02 and 03 ) AND all lines from the last occurrence of Text_2 ( so, lines 18, 19 and 20 ) = case B

          • All lines till the last occurrence of Text_1 ( so, from lines 01 to 09 ) AND all lines from the first occurrence of Text_2 ( so, from lines 12 to 20 ) = case C

          • All lines till the last occurrence of Text_1 ( so, from lines 01 to 09 ) AND all lines from the last occurrence of Text_2 ( so, lines 18, 19 and 20 ) = case D

          Just, tell me which case ( A, B, C or D ), we’ll have to find out the regex for ?

          Keep in mind, that I, implicitly, suppose that :

          • No string Text_1 may occur, after the first occurrence of string Text_2 !!

          • The strings Text_1 and/or Text_2 may appeared alone, in a line

          See you later,

          Best regards

          guy038

          P.S. :

          Anyway, Vasile, I updated my reply, one hour, later !

          Here are, below, the solution to the FOUR cases, given the exact previous example text, above.

          We just have to make, successively, each quantifier Star, lazy or greedy ! So :

          • Case A : SEARCH = (?s).*?Text_1\R(.*?)Text_2.* , which keeps the lines 04 to 11, only

          • Case B : SEARCH = (?s).*?Text_1\R(.*)Text_2.* , which keeps the lines 04 to 17, only

          • Case C : SEARCH = (?s).*Text_1\R(.*?)Text_2.* , which keeps the lines 10 to 11, only

          • Case D : SEARCH = (?s).*Text_1\R(.*)Text_2.* , which keeps the lines 10 to 17, only

          NOTE :

          • For these four cases, the replacement regex is, simply, \1 OR $1
          1 Reply Last reply Reply Quote 0
          • V
            Vasile Caraus
            last edited by Vasile Caraus Sep 13, 2016, 6:11 PM Sep 13, 2016, 6:11 PM

            guy, works great. But if I want to replace the entire line from fisrt part (?s).*?Text_1\R(.*?), so not only from a word, but the entire line that contains that word

            1 Reply Last reply Reply Quote 0
            • S
              Scott Sumner
              last edited by Sep 13, 2016, 6:19 PM

              guy038 should get paid a consulting rate for his excellent quality and quantity of answers! His perseverance is remarkable!

              1 Reply Last reply Reply Quote 2
              • V
                Vasile Caraus
                last edited by Sep 13, 2016, 7:46 PM

                Guy, is a very talented and smart. He is the one that helps notepad users to grow and develop, step by step.

                Maybe someday, somebody will need the answers of my questions, and Guy is the one that make possible !

                Evolution starts with questions…and answers !

                by the way, I am not a programmer, in fact, I don’t have almost any connection with this domain. But, I learn basic, which helps me a lot in other way ! Thank you Guy038 !

                1 Reply Last reply Reply Quote 0
                • G
                  guy038
                  last edited by guy038 Sep 14, 2016, 3:43 AM Sep 13, 2016, 8:10 PM

                  Hello Vasile and Scott,

                  Yeah, Scott, you’re right about it ! So, I could drink some more beers, as the weather is quite hot, presently, in Grenoble !!

                  No problem, Vasile. So, I’m starting with the original text below :

                  Line 01
                  Line 02
                  Line 03 Text_1 Line 03
                  Line 04
                  Line_05
                  Line 06 Text_1 Line 06
                  Line 07
                  Line 08
                  Line 09 Text_1 Line 09
                  Line 10
                  Line 11
                  Line 12 Text_2 Line 12
                  Line 13
                  Line 14
                  Line 15 Text_2 Line 15
                  Line 16
                  Line 17
                  Line 18 Text_2 Line 18
                  Line 19
                  Line 20
                  

                  As you can see, this time, the strings Text_1 and Text_2, in lines 03, 06, 09, 12, 15 and 18 are, all, embedded in the template Line ##......Line ##


                  I keep the same principle, using lazy and greedy quantifiers star *. That leads to the four regexes, below :

                  • Case A : SEARCH = (?s).*?Text_1(?-s).*\R((?:.*\R)*?).*Text_2(?s).* , which keeps the lines 04 to 11

                  • Case B : SEARCH = (?s).*?Text_1(?-s).*\R((?:.*\R)*).*Text_2(?s).* , which keeps the lines 04 to 17

                  • Case C : SEARCH = (?s).*Text_1(?-s).*\R((?:.*\R)*?).*Text_2(?s).* , which keeps the lines 10 to 11

                  • Case D : SEARCH = (?s).*Text_1(?-s).*\R((?:.*\R)*).*Text_2(?s).* , which keeps the lines 10 to 17

                  Remark :

                  • Remember that an in-line modifier keeps set, till an opposite modifier is met in the regex or till the end of the regex is reached !

                  • The replacement regex has not changed : \1 or $1

                  Cheers

                  guy038

                  P.S… :

                  If some parts of the regexes seems too difficult, just ask me for further information ! It’s, simply, a question of mind’s gymnastics, that anyone can learn about !

                  Also, try, to visualize the position of the regex engine, while executing the regex, especially when Look-Around ( Look-Behind or Look-Ahead ) are used. Indeed, in that case, the location of the regex engine does NOT change while evaluating the look-around !

                  For instance, with the subject text This is a simple text to visualize the cursor location of the regex engine

                  Then, the regex (?-s)(?=.*regex).{4} matches the four letters of this sentence ( the word this ). Let’s us split the process :

                  • Cursor location is just before the first letter T of the text

                  • The regex engine tries to verify if, from the present cursor location, the look-ahead. In other words, if there is, further on, on the same line, the string regex ?

                  • As this condition is true, the regex engine goes on, executing the following regex code .{4}

                  • But the working position of the regex engine, is, STILL, before the first letter T of the text !

                  • Therefore, the regex engine matches the first four characters of the subject string, that is to say, the word this


                  Note that IF the word regex would NOT have been found, in the text, the regex engine would have delivered the message :
                  Can't find the text "(?-s)(?=.*regex).{4}" !

                  1 Reply Last reply Reply Quote 0
                  • V
                    Vasile Caraus
                    last edited by Sep 14, 2016, 6:42 AM

                    thanks a lot Guy !

                    1 Reply Last reply Reply Quote 0
                    • V
                      Vasile Caraus
                      last edited by Sep 18, 2016, 1:32 PM

                      hello Guy. And If I want to matc (in the last formulas) the first instance of Text_1 and the last instance of Text_2?

                      1 Reply Last reply Reply Quote 0
                      • G
                        guy038
                        last edited by Sep 19, 2016, 10:46 PM

                        Hi Vasile,

                        I, first, thought that the regex (?s).*?\KText_1|.*\KText_2 would give you the exact matches that you said :

                        And If I want to match (in the last formulas) the first instance of Text_1 and the last instance of Text_2?

                        Unfortunately, when using the search functionality, only, this regex matches any string Text_1, then the last string text_2 ! And, I was not able to get the right regex, which could find, in the current file, the first instance of Text_1, then the last instance of Text_2 :-((

                        However, the regex (?s).*?\KText_1.*Text_2 allows us to select, in one go, all the gap, between these two specific boundaries, included !

                        Best Regards,

                        guy038

                        1 Reply Last reply Reply Quote 0
                        • V
                          Vasile Caraus
                          last edited by Vasile Caraus Feb 16, 2021, 9:23 AM Feb 16, 2021, 9:23 AM

                          hello again. I have many of <tr></tr> tags on a html page. I want to select with regex only this first instance of <tr> tags. I made a regex, but this formula selects both <tr>. tags. I want only the first one, not the second one with Other Code

                          FIND: \b<tr>[\s\S]+</tr>\b

                          <tr>
                          <td class="right">On December 15, 2012, in <a href="https://mywebsite.com/index.html" title="See all articles here" class="external" rel="category tag">Expert-Expert</a>, by Michael Ende</td>
                          `</tr>
                          

                          and more

                          <tr>
                          Other Code
                          </tr>
                          
                          V 1 Reply Last reply Feb 16, 2021, 10:50 AM Reply Quote 0
                          • Terry RT
                            Terry R
                            last edited by Feb 16, 2021, 10:29 AM

                            @Vasile-Caraus said in Regex: Select only the first instance of search results / first match:

                            FIND: \b<tr>[\s\S]+</tr>\b

                            The simplest change I can see is to put a ? behind the + character as your regex is greedy. I presume it is currently going to the last </tr> in the file.

                            Also as far as I can see the \s\S combination means every character including CR and LF one’s. The whole thing could be rewritten as (?s)\b<tr>.+?</tf>\b.

                            I’m not on a PC to currently check my answer so apologies if I have it slightly wrong.

                            Terry

                            1 Reply Last reply Reply Quote 0
                            • V
                              Vasile Caraus
                              last edited by Feb 16, 2021, 10:45 AM

                              @Terry-R said in Regex: Select only the first instance of search results / first match:

                              (?s)\b<tr>.+?</tf>\b

                              your (?s)\b<tr>.+?</tr>\b is not working :(

                              I also try something different, also not working :( (?:^(?ms)(<tr>).*?(</tr>))

                              Terry RT 2 Replies Last reply Feb 16, 2021, 10:57 AM Reply Quote 0
                              • V
                                Vasile Caraus @Vasile Caraus
                                last edited by Vasile Caraus Feb 16, 2021, 10:51 AM Feb 16, 2021, 10:50 AM

                                I also try another combination, not working (?-s)(\b(?!^<tr>(.+)</tr>)

                                :((

                                <tr>
                                <td class="right">On December 15, 2012, in <a href="https://mywebsite.com/index.html" title="See all articles here" class="external" rel="category tag">Expert-Expert</a>, by Michael Ende</td>
                                </tr>
                                

                                code

                                <tr>
                                Other Code
                                </tr>
                                
                                1 Reply Last reply Reply Quote 0
                                • Terry RT
                                  Terry R @Vasile Caraus
                                  last edited by Terry R Feb 16, 2021, 10:58 AM Feb 16, 2021, 10:57 AM

                                  @Vasile-Caraus said in Regex: Select only the first instance of search results / first match:

                                  your (?s)\b<tr>.+?</tr>\b is not working :(

                                  What does it do? Does it select anything. And sorry for the typo with the tf which I see you caught.
                                  The (?s) is necessary to cross lines. As you had \b I also included them although they could both be removed as a test.

                                  Terry

                                  V 1 Reply Last reply Feb 16, 2021, 1:51 PM Reply Quote 0
                                  • V
                                    Vasile Caraus
                                    last edited by Feb 16, 2021, 1:37 PM

                                    I believe only @guy038 can find a good answer :)

                                    Alan KilbornA 1 Reply Last reply Feb 16, 2021, 1:41 PM Reply Quote 0
                                    • Alan KilbornA
                                      Alan Kilborn @Vasile Caraus
                                      last edited by Alan Kilborn Feb 16, 2021, 1:42 PM Feb 16, 2021, 1:41 PM

                                      @Vasile-Caraus said in Regex: Select only the first instance of search results / first match:

                                      I believe only @guy038 can find a good answer

                                      Nice kick in the teeth for Terry, who was trying to help you…
                                      :-) not withstanding.

                                      1 Reply Last reply Reply Quote 2
                                      • V
                                        Vasile Caraus @Terry R
                                        last edited by Vasile Caraus Feb 16, 2021, 1:51 PM Feb 16, 2021, 1:51 PM

                                        @Terry-R I want to select everything from <tr> to </tr> but only one instance, the first instance, because I have many tags starting with <tr> and close with </tr>

                                        Alan KilbornA PeterJonesP 2 Replies Last reply Feb 16, 2021, 2:21 PM Reply Quote 0
                                        • Alan KilbornA
                                          Alan Kilborn @Vasile Caraus
                                          last edited by Feb 16, 2021, 2:21 PM

                                          @Vasile-Caraus

                                          Wouldn’t (?s)\A.*?<tr>.*?</tr> work to get only the first?

                                          1 Reply Last reply Reply Quote 1
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