------ art_70355_30315321.1129531111646 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Zach, if an element repeats more that once, itll double up in the output array. need to add a .uniq on the end irb(main):165:0> a = [1,2,3,4,5,3,5,3,5] => [1, 2, 3, 4, 5, 3, 5, 3, 5] irb(main):166:0> t=[]; a.delete_if{ |e| r=(not t.include? e); t.push(e); r } => [3, 5, 3, 5] That aside, this one is a little shorter, and seems to benchmark a touch faster as well. irb(main):180:0> a=[1,2,3,4,5,3,5,3,5] => [1, 2, 3, 4, 5, 3, 5, 3, 5] irb(main):181:0> t=[]; a.select{ |e| r=t.include?e; t<<e; r }.uniq => [3, 5] irb(main):182:0> a => [1, 2, 3, 4, 5, 3, 5, 3, 5] Mark ------ art_70355_30315321.1129531111646--