Hello Monks! It looks like today is my day in having problems I cannot resolve. It looks like two years without coding + problems in understanding complex structure might generate a lot of problems!
So, here's my problem. I have this kind of input:

frog-n    as    novelty-n    5.8504
frog-n    be    yellow-n    6.1961
frog-n    be-1    Asia-n    5.0937
frog-n    coord    zebra-n    5.9279
frog-n    coord-1    Canuck-n    6.3363
frog-n    nmod-1    mule-n    4.2881
amphibian-n    success-1    surprising-j    14.6340
amphibian-n    such_as    alligator-n    11.5265
amphibian-n    than    work-n    5.9948
amphibian-n    though    stalk-n    13.2228
[download]

and my output should be a "matrix", as to say, made like the following:

frog-n as_novelty-n,5.8504    be_yellow-n,6.1961    be-1_Asia-n,5.0937
+    coord_zebra-n,5.9279    coord-1_Canuck-n,6.3363    nmod-1_mule-n,
+4.2881
amphibian-n    success-1_surprising-j,14.6340    such_as_alligator-n,1
+1.5265    than_work-n,5.9948    though_stalk-n,13.2228
[download]

basically, the first element contained in the first column of the input file is the key and a joint expression between the element contained in the 2nd and 3rd column, with the corresponding score

I managed to do the following:

my $prefix = shift;
my $input = shift;

my $file = $prefix . ".txt";


if (-e $file) {
    print STDERR "$file already exists, deleting previous version\n";
    `rm -f $file`;
}

my $debug=0; #Variabile di debug. Vale 1 in fase di debug, si usa per 

my %seen = ();
my @global_els = ();
my @row_els = ();
my %score_of = ();
my $row_el;
my $gram;
my $col_el;
my $score_of;
my $score;
my $global_el;

open INPUT,$input;

while(<INPUT>){
    chomp;
    ($row_el,$gram,$col_el,$score) = split "[\t ]+",$_;
    $global_el=$gram."_".$col_el;
    
      if (!($seen{"glob"}{$global_el}++)) {
    push @global_els,$global_el;
    }
    if (!$seen{"row"}{$row_el}++) {
    push @row_els,$row_el;
    }
    $score_of{$row_el}{$global_el} = $score;

    if($debug){
        print "Check:".$row_el."=>".$global_el."=>".$score;
    }    
}
close INPUT;




#@global_els = ();
#@row_els = ();

open MATRIX,">$file";
#my $score_b=$score_of{$row_el}{$global_el};
foreach $row_el (@row_els) {
    print MATRIX "\t",$row_el;
    foreach $global_el (@global_els) {
        print MATRIX "\t",$global_el;
    print MATRIX ",",$score_of{$row_el}{$global_el};
    }
    print MATRIX "\n";
}
close MATRIX;
[download]

But my output is wrong, since all the so-called joined elements appear in both the lines, even if they are not related to the element in that line. For example, the output I get using the data above is like:

frog-n as_novelty-n,5.8504    be_yellow-n,6.1961    be-1_Asia-n,5.0937
+    coord_zebra-n,5.9279    coord-1_Canuck-n,6.3363    nmod-1_mule-n,
+4.2881    success-1_surprising-j,    such_as_alligator-n,    than_wor
+k-n,    though_stalk-n,
amphibian-n    success-1_surprising-j,14.6340    such_as_alligator-n,1
+1.5265    than_work-n,5.9948    though_stalk-n,13.2228     as_novelty
+-n,    be_yellow-n,    be-1_Asia-n,    coord_zebra-n,    coord-1_Canu
+ck-n,    nmod-1_mule-n,
[download]

What did I get wrong? How can I improve it?
Thanks everyone,
Giulia