Hello fasoli,

Here is one approach:

#! perl
use strict;
use warnings;
use Data::Dump;

my %data;
my %y_values;

while (<DATA>)
{
    my ($x, $y) = split;
    $x = sprintf "%.2f", $x;
    $y = sprintf "%.2f", $y;
    push @{ $data{$x} }, $y;
    $y_values{$y}++;
}

dd \%data;
my @x = sort { $a <=> $b } keys %data;

print "\n";
print "\t$_" for @x;
print "\n", '-' x 29, "\n";

for my $y (sort { $a <=> $b } keys %y_values)
{
    print $y;

    for my $x (@x)
    {
        my $count = 0;
        $_ == $y && ++$count for @{ $data{$x} };
        print "\t$count";
    }

    print "\n";
}

print '-' x 29, "\n";

__DATA__
 0.1234567890  1.2345678901
52.2456789012 17.2345678901
 0.1234567890  1.2345678901
22.3456789012  3.4567890123
22.35          1.234
[download]

Output:

 1:59 >perl 1635_SoPW.pl
{ "0.12" => [1.23, 1.23], "22.35" => [3.46, 1.23], "52.25" => [17.23] 
+}

        0.12    22.35   52.25
-----------------------------
1.23    2       1       0
3.46    0       1       0
17.23   0       0       1
-----------------------------

 1:59 >
[download]

The first step is to read the data into a hash of arrays, while also keeping track of Y values in a separate hash. (This is just for convenience). The next step is to sort the X and Y values. Once this is done, the final step generates the matrix by counting the number of occurrences of each X-Y pairing.

Hope that helps,