Hi Monks,
I am trying to accumulate the value of HoH (%bucket) below . Such that this code

use strict;
use warnings;
my %bucket = (
      key1 =>   {   '1' => 3},
       key2 =>  {  '1' => 3,
                   '2' => 2},
      key3 =>   {   '1' => 11,
                    '2' => 36}
  );

my %spair = ();
my $cnt =0;

  foreach my $kmer ( keys %bucket  )
  {
     foreach my $si (keys %{$bucket{$kmer}})
     {     foreach my $sn (keys %{$bucket{$kmer}}) 
       { 
         next if exists $spair{$sn."-".$si};
         if ( $si == $sn )
         {
            $cnt = $bucket{$kmer}{$si};
         }
         else
         {
                $cnt = $bucket{$kmer}{$si}*$bucket{$kmer}{$sn};
         }
        $spair{$si."-".$sn} +=$cnt; 
            }
     }     # ----- end foreach ----- 
  }  # ----- end foreach -----

use Data::Dumper;
print Dumper \%spair;
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would give:

$VAR1 = {
          '1-1' => 17, # 3+3+11
          '2-2' => 38, # 2+36
          '1-2' => 402 # (3*2)+(11*36), this is correct already
        };
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instead of:

$VAR1 = {
          '1-1' => 3,  #wrong
          '2-2' => 2,  #wrong
          '1-2' => 402 #correct
        };
[download]

I've been playing around with it, I still can't see where it went wrong. Your advice is very valuable for me. Thanks so much beforehand.

Regards,
Edward