#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my @to_proc = (
               'I1 TTAT',
               'I1 TTTT',
               'I1 TAGT',
               'I2 TTAT',
               'I3 TAGT',
              );
my $d  = 1;
my %transaction_map_mismatch;
read_trans_array_mismatch(\%transaction_map_mismatch, \@to_proc,$d);

print Dumper \%transaction_map_mismatch;


#--------Sub------------
sub read_trans_array_mismatch
{
  my $transaction_map_ref = shift;
  my $transaction_array   = shift;
  my $d                   = shift;

  for ( my $i = 0; $i< @{$transaction_array}; $i++ )
  {


    my @data = split(/\s/,$transaction_array->[$i]);
    my ($tid, $item) = @data;

    for ( my $j = 0 ; $j < @{$transaction_array} ;$j++ )
    {

      my ($tid2, $item2) = split(/\s/,$transaction_array->[$j]);

      if ( hd($item,$item2) <= $d )
      {
         $$transaction_map_ref{$item}{$tid}++;
         last;
      }

    }
  }

}

sub hd
{
        #Hamming Distance of two strings
        #String length is assumed to be equal
        
        # Following djohntson advice, changed var declaration 
        # from: my ($a, $b)
      
        my ($k,$l) = @_;
        my $len = length ($k);
        my $num_mismatch = 0;

        for (my $i=0; $i<$len; $i++)
        {
         ++$num_mismatch if substr($k, $i, 1) ne substr($l, $i, 1);
        }

        return $num_mismatch;
}

##</code><code>##

__END__

$VAR1 = {
          'TAGT' => {
                      'I1' => 1,
                      'I3' => 1
                    },
          'TTTT' => {
                      'I1' => 2, #From TTAT and TTT in I1, 
                                 #because their HD <= $d
                      'I2' => 1,
                    },
          'TTAT' => {
                      'I2' => 1,
                      'I1' => 2  # also From TTAT and TTT in I1
                    }
        };


##</code><code>##

# Which is the same as $d = 0
$VAR1 = {
          'TAGT' => {
                      'I3' => 1,
                      'I1' => 1
                    },
          'TTTT' => {
                      'I1' => 1
                    },
          'TTAT' => {
                      'I2' => 1,
                      'I1' => 1
                    }
        };