Seriously? The code runs fine for me.

The expected output of the code or what I'd like. Since I'm not sure if I'm on the right track with the code, what I'd like are three sets with 5,7,10,10, 50, and 70,72,75,79,80.

I'm not sure how else to explain this - between the code I'm stuck on, the use case, and abstract....?

What is significant about those groups of numbers?

Perl can't mind read.

Michael

Oh, they're 'close' together.

Not sure if this is any use but is does give the expected output. It loops through the sorted list working out the effect of adding each to 'current group average'. If change is greater than the value 'diff' it starts a new group

#!perl
use strict;

my @data = (10,7,5,10,50,70,75,72,79,80);
my @arr = sort {$a<=>$b} @data;
my $diff = 2; # group closeness

my @avg; #[count,sum]
my @grp;
my $g=0;

for my $i (0..$#arr){
  my $val = $arr[$i];
  #print "value $val\n";
  if ($i == 0){
    push @{$grp[$g]},$val;
    $avg[$g] = [1,$val];
  } else {
    #work out new average with this element
    my ($n,$sum) = @{$avg[$g]};
    #print "count $n sum $sum\n";
    my $avg = $sum/$n;
    my $new_avg = ($sum+$val)/($n+1);
    if (abs($new_avg - $avg) < $diff){
      # join group
      push @{$grp[$g]},$val;
      $avg[$g] = [$n+1,$sum+$val];
    } else {
      # start new group
      ++$g;
      push @{$grp[$g]},$val;
      $avg[$g] = [1,$val];
    }
  }
}

for (@grp) {
  print join ',',@$_,"\n";
}
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POJ