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Is there a way in Notepad++ to delete every other or nth line? I have a massive list of data and I need to reduce the size.

The data itself is not that important and out of a list of 10,000 items I only need a selection of 5,000

fightstarr20
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    Notepad++ has no such function. but writing a program that would delete every other line would be only few lines long. – zoran404 Jul 18 '13 at 22:49
  • Im thinking a batch file might be the simplest option for my situation – fightstarr20 Jul 18 '13 at 22:51
  • Another idea is to search for [`\R\K.+\n?`](https://regex101.com/r/RJD2Tg/1) and replace with emptystring. Supposed to even work if last line is unterminated (make sure to uncheck [ ] `.` *matches newline* in the NP++ replace dialogue). – bobble bubble Aug 13 '22 at 11:44

7 Answers7

140

I'm not sure Notepad++ is the best tool for this, but using the Power of Regex, we should be able to do it.

Open the replace menu, fill in ([^\n]*\n)[^\n]*\n in the "Find what" box and $1 in the "Replace with" box. Then select regular expression for the search mode, click replace all and every second line is deleted.

You can build similar regexes if you want to do something similar. For example, (([^\n]*\n){a})[^\n]*\n will replace every nth line if you replace a by n - 1 and [^\n]*\n([^\n]*\n) will let you keep even lines instead of odd ones.

Jasper
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  • Thanks, as strange as this is, I was using GPS points from a tracking app on my phone, exported as KML and imported to Litchi Fly Hub for my drone, however, there were way to many points, and this was able to reduce those & still keep route – drooh Jan 31 '18 at 21:00
  • So "[^\n]*\n" is for finding a whole line with the newline symbol. Would it be the same as "^.*\n" ? – Kardaw Oct 18 '20 at 20:17
  • ... I guess yes, more or less, because [^\n] means find any symbol that is not a "\n" – Kardaw Oct 18 '20 at 20:21
  • @Kardaw There's a small difference: depending on whether multiline mode is on and on the regex flavor, the dot may also match newlines, and thus your regex may also match two (or any other number) of lines instead of one. I think that's not a problem here, but it could cause unwanted effects or performance degradation if there is a way for the query to need to backtrack. I like to keep my regexes flavor-independent where possible and I don't like performance pitfalls, thus I wrote the longer query. – Jasper Oct 19 '20 at 11:56
  • A little "issue" [if last line not terminated](https://regex101.com/r/BpJkRF/1). Can simply be solved by making the final `\n` *optional* [like this](https://regex101.com/r/TaDU2i/1). – bobble bubble Aug 13 '22 at 11:50
32

You can try to use a Macro.

  1. Start recording Macro
  2. Press down n-times
  3. Press Shift+End
  4. Press delete two times
  5. Stop recording Macro
  6. Run Macro until end of file
bsmk
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8

I came across this issue myself. What worked for me, also using the Find/Replace function, is to:

  1. Ctrl F and go to Replace
  2. In search mode, select "Extended (\n, \r, \t .. )"
  3. Find what: \n\n
  4. Replace with: \n
  5. Replace All
Steven C
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7

I think you can do this with awk if you're on a unix style platform:

awk 'NR % 2 == 0' file > outfile

NR is the line number, so this will just say "if the line is divisible by 2 stick it in newfile."

If you are on windows, I think the answer here would work:

batch file to keep one of ten lines

Community
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Evan Reynolds
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5

Mirroring that question, here is a solution for most OS using "find & replace" :

  • Set the cursor on the first line
  • Open the replace dialog (Ctrl + H)
  • Select "Regular expression"
  • Find what: (.+\R).+(\R|$)
  • Replace with: $1
  • Press "Replace All"

Note:

  • No "Wrap around"
  • \R is the Unix/Mac/Windows regex for "end of line"
Undergeeker
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0

I don't think there is a feature in Notepad++ that will automatically delete every other (or every nth) line, but if you wrote a short conversion program it would only take a few minutes.

The pseudocode would look something like this:

1. Create a StreamReader and StreamWriter (make sure you are not trying to read from
   and write to the same file)
2. While (StreamReader is reading lines) increment i. You could mod it by whatever 
   number n you wanted in order to delete certain lines. Then have a conditional clause
   that would write out if i%n == 0 or whatever you specify.
3. Close the program.

That doesn't exactly answer your question, but I hope it helps.

khinkle
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Another way, you can use the command line cc.dl 5.5 of ConyEdit(a plugin) to delete the very fifth line of each group, five lines for each group.

Hunter
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