Hi there
I have been trying to do the following
Taking 'ob1' as the 'object of interest' I have a text file which looks like this 
ob1, ob2, 34
ob1, ob3, 56
ob1, ob4, 12
ob1, ob5, 78
ob1, ob6, 23
ob3, ob1, 56
ob7, ob1, 23
ob8, ob1, 12
ob9, ob1, 90
etc ...

[download]
and what I need is to create a matrix like this 
     ob1   ob2   ob3  ob4  ob5  ob6  ob7  ob8  ob9
ob1   0     34    56   12   78   23   23   12   90
ob2  34
ob3  56
ob4  12
ob5  78
ob6  23
ob7  23
ob8  12
ob9  90

[download]
And for any 'duplicate results' like these 
ob1, ob3, 56
ob3, ob1, 56

[download]
Only take the first instance (as the result is the same, regardless of the direction).
Ob2 then becomes the 'object of interest' and column two and row two is populated in the same way (but with different values potentially) as the first column and first row was populated with ob1 was the 'object if interest'. And the ob3 becomes the 'object of interest' until the matrix is completely filled. In some cases, there may be some missing values (for example there may not be a 'ob4 ob5' value and I need to take that into account - perhaps by printing 'NULL' or something).
I asked for help from Perl Monks yesterday and this is the code I have so far 
#!/usr/local/bin/perl
use strict;

my $data = $ARGV[0];

# open file here

open(DATA, "$data") || die "cant open file for reading\n";

my %table;
my %rows;
my %cols;

for(<DATA>) {
  my($row,$col,$val) = split ',';
  $table{$row}{$col} = $val;
  $rows{$row}++;
  $cols{$col}++;
}

for my $col (sort keys %cols) {
  print "\t$col";
}
print "\n";

for my $row (sort keys %rows) {
  print "$row\t";
  for my $col (sort keys %cols) {
    print $table{$row}{$col} if defined $table{$row}{$col};
    print "\t";
  }
  print "\n";
}

[download]
The results I get using the code above is: 
               ob1 ob2 ob3 ob4 ob5 ob6


ob1                 34
        56
        12
        78
        23

ob3         56

ob7         23

ob8         12

ob9         90

[download]
Which isn't quite what I need, but I don't know how to fix it (due to my blind spot regarding hashes I suspect).
Any suggestions much appreciated.

In reply to printing out a matrix for a data list by Angharad

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