note linseyr Actually, my output would be: <code> $chr $begin $end $id $average </code> But I just wanted to start with calculating. I would like to calculate the average difference between the 2 columns (5 and 6) for the same id. So for line 3,4,5 I would like to calculate the average difference between column 5 and 6. And for the lines for which only one line has that id, like line 1 I just want to calculate the difference between column 5 and 6, since there is no average to calculate. I only want to output the lines that have a average difference > 0.2 994977 994984