This may be an oversimplification, but here is one idea:

#!/usr/bin/perl -w 
use strict;

open FIN,"<dataset.dat" or die "dataset.dat:$!";
my $buckets={};

while(my $line=<FIN>){
    chomp $line;
    my @f=split(",",$line);
    unless (exists($buckets->{$f[1]}){
        $buckets->{$f[1]} = { count => 0, where =>[ ] };
    }
    if ( $f[4] > 0 ) { 
         $buckets->{$f[1]}->{count}++;
         push @{$buckets->{$f[1]}},$f[0];
    }
}
close FIN;
foreach my $key (sort keys %$buckets){
      next unless $buckets->{$key}->{count} > 0 ;
      printf "%s\t%d\t%s\n",
                $key,$buckets->{$key}->{count},
                join(",",sort @{$buckets->{$key}->{where}});
}

#
####################################################### done
[download]

Caveat: not tested.. do not use for the control of a nuclear missile launch system.