I don't understand the purpose of the  \K operator in the
    / ( .{9} [ATCG]{10} G \K G ) /gsx
regex in your code. It doesn't seem to have any effect except WRT $& and ${^MATCH}, which aren't used in the code: 

c:\@Work\Perl>perl -wMstrict -MData::Dump -le
"my $line =
   'AAAATTTTCCCCGGGGAAAGGxAAAACCCCTTTTGGGGAAAGGxTTTTAAAACCCCGGGGAAAGG'
   ;
 my %unique_data;
 my $count;
 while ( $line =~ / ( .{9} [ATCG]{10} G \K G ) /gsxp ) {
   print qq{>crispr_@{[ ++$count ]} '$1' ($&) (${^MATCH})}
     unless $unique_data{$1}++;
   }
 ;;
 dd \%unique_data;
"
>crispr_1 'AAAATTTTCCCCGGGGAAAGG' (G) (G)
>crispr_2 'AAAACCCCTTTTGGGGAAAGG' (G) (G)
>crispr_3 'TTTTAAAACCCCGGGGAAAGG' (G) (G)
{
  AAAACCCCTTTTGGGGAAAGG => 1,
  AAAATTTTCCCCGGGGAAAGG => 1,
  TTTTAAAACCCCGGGGAAAGG => 1,
}

[download]
Can you please give me some insight on this? Is  \K simply a leftover from a previous version of the code?

Give a man a fish:  <%-{-{-{-<

In reply to Re^2: unique sequences by AnomalousMonk
in thread unique sequences by Anonymous Monk

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