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Deleting n number of instances of a pattern after x number of them

Posted on 2013-11-06
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Last Modified: 2013-11-08
I have a file that contains data in this form (this is a shorten version)

<product>
<isbn>0000000001</isbn>
<contributor>
<role>A01</role>
<author>Lee, Stan</author>
</contributor>
<contributor>
<role>A01</role>
<author>Steranko, Jim</author>
</contributor>
<contributor>
<role>A01</role>
<author>Adams, Neal</author>
</contributor>
<contributor>
<role>A01</role>
<author>Smith, Barry</author>
</contributor>
</product>

The problem is that sometimes the number of author composites can be as high as 50 - if not more - and I only need to the first 5. Is there a regular expression (since I'm using Perl) to keep a set number of <contributor> ... </contributor> (say 5) and delete the rest?
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Question by:hadrons
[X]
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8 Comments
 
LVL 84

Accepted Solution

by:
ozo earned 500 total points
ID: 39628853
$_='
<product>
<isbn>0000000001</isbn>
<contributor>
<role>A01</role>
<author>Lee, Stan</author>
</contributor>
<contributor>
<role>A01</role>
<author>Steranko, Jim</author>
</contributor>
<contributor>
<role>A01</role>
<author>Adams, Neal</author>
</contributor>
<contributor>
<role>A01</role>
<author>Smith, Barry</author>
</contributor>
</product>';
s{(<product>((?!</product>).)*?(<contributor>.*?</contributor>\s*){5})((?!</product>).)*}{$1}sg;
print;
0
 
LVL 9

Expert Comment

by:Derek Jensen
ID: 39629120
Might I suggest a small modification to the regex above?

s{<product>.*?((<contributor>(.+?)</contributor>){1,5}).*?(?<!</product>)}{$1}sig;

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0
 

Author Comment

by:hadrons
ID: 39630704
Hi, the regular expression work great when I used it the form Ozo provided (I did include the modification provided by bigdogman,) but I want to integrate this expression in a large script I have (see below) and the substitutions weren't made.  

#!/usr/bin/perl

use strict;
use Encode qw(encode decode);
use File::Copy;


## start process 5
system ("echo processing part 5 of 10: Editing of parsed files \.\.\.");
my @files = glob("Edit19");      
foreach my $file(@files) {
          system ("echo currently processing file: $file");
                      open FILE, '<:encoding(UTF-8)', $file or warn "Can't open $file: $!";  
                      open PARSED, '>:encoding(UTF-8)', ($file . "edited.txt") or warn "Cannot open file for write: $!";  

while (<FILE>) {

s{(<product>((?!</product>).)*?(<contributor>.*?</contributor>\s*){1,5})((?!</product>).)*}{$1}sg;


print PARSED;
}
}
close FILE;
close PARSED;
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LVL 9

Expert Comment

by:Derek Jensen
ID: 39630810
My apologies, I gave you the wrong group #. Try this one:

s{<product>(?!<\/product>).*?((<contributor>.*?<\/contributor>\s*){1,5})(?!<\/product>).*}{$1}sig;

Open in new window

0
 

Author Closing Comment

by:hadrons
ID: 39631988
I worked with some files and the pattern match did the substitutes perfectly; there were some problems with the newlines, but that could be due to the engine I'm using
0
 
LVL 84

Expert Comment

by:ozo
ID: 39632810
$/="";
while (<FILE>) {
0
 

Author Comment

by:hadrons
ID: 39634516
Excellent
0
 

Author Comment

by:hadrons
ID: 39634919
It wasn't provided in the example I gave, but the regular expression is deleted additional data after the first 5 contributors to the </product>, so for example:

<product>
<isbn>0000000001</isbn>
<contributor>
<role>A01</role>
<author>Lee, Stan</author>
</contributor>
<contributor>
<role>A01</role>
<author>Steranko, Jim</author>
</contributor>
<contributor>
<role>A01</role>
<author>Adams, Neal</author>
</contributor>
<contributor>
<role>A01</role>
<author>Smith, Barry</author>
</contributor>
<additional>
<additional data>1</additional data>
</additional>
</product>

Would leave just this:

<product>
<isbn>0000000001</isbn>
<contributor>
<role>A01</role>
<author>Lee, Stan</author>
</contributor>
<contributor>
<role>A01</role>
<author>Steranko, Jim</author>
</contributor>
<contributor>
<role>A01</role>
<author>Adams, Neal</author>
</contributor>
<contributor>
<role>A01</role>
<author>Smith, Barry</author>
</contributor>
</product>

With whatever was under it deleted also; is there way to correct this?
0

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