$list = '1,2,3,4,5,6,7,8';

@odds = grep $_ % 2, split(/,/, $list);
@evens = grep not($_ % 2), split(/,/, $list);

##</code><code>##

$list = 'a,b,c,d,e,f,g,h';

$i=0;
@pos1 = grep not($i++ % 2), split(/,/, $list);

$i=0;
@pos2 = grep $i++ % 2, split(/,/, $list);