I think I am getting it now... I so dumb I was trying out a way to add them up in the matrix, when your simple solution is to add them up before! Whay didn't I think of that first! 

list
----
HAT    KNIFE    1
HAT    KNIFE    7
BALL   KNIFE    3
CAT    CLOTH    1
DOG    CLOTH    2
    
code
----    
my %matrix;
while (<>) {
    my ($id1, $id2, $int) = split;
    $matrix{$id1}{$id2} += $int;
}

foreach $key1 (keys %matrix) {
        foreach $key2 (keys %{%matrix->{$key1}}) {
                print "\$matrix{$key1}{$key2} = $matrix{$key1}{$key2} 
+";                            
                } 
        print"\n";                                                    
+                               
        }

output
------
$matrix{CAT}{CLOTH} = 1
$matrix{DOG}{CLOTH} = 2
$matrix{HAT}{KNIFE} = 8
$matrix{BALL}{KNIFE} = 3

[download]
Last question please.. do you have a good code snippet to put it in the matrix afterwoods please? 

              CLOTH     KNIFE
   BALL        0         3
   HAT         0         8
   DOG         1         0
   CAT         1         2

[download]

In reply to Re^4: Associated lists to matrices - and accumalted integers by jaybode
in thread RESOLVED - Associated lists to matrices - and accumalted integers by jaybode

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