array looks like this:
category_Title Words_1 
category_Title Words_2 
category_Title Words_3 
category_Title Words_4 

($sub1, $sub2, $sub3) = split (/\_/, @array,3);
$sub3 = sort { $b <=> $a } $sub3;

doesn't work. i've also tried: 
my @newarray = ($sub1,$sub2,$sub3);
@newarray = sort { $a->[2] cmp $b->[2] } @newarray;