Dear R-Family, I have a data-set of the following format. I am only presenting a part of it. Date A B C D 1-Jan-61 0.00 1.27 8.128 0.25 2-Jan-61 6.10 9.144 94.742 15.49 3-Jan-61 0.00 0.508 1.27 0.00 4-Jan-61 0.00 0 NA 0.00 5-Jan-61 0.00 0 0 0.00 6-Jan-61 0.00 NA 0 0.00 7-Jan-61 0.00 0 0 0.00 8-Jan-61 0.00 NA 0 0.00 9-Jan-61 0.00 NA 0 NA 10-Jan-61 0.00 4.064 4.826 0.76 You can see that each column has some NAs in it, What i want to do is to learn that which date has NA for each column. Here it should be something like the following A B C D 6-Jan-61 4-Jan-61 9-Jan-61 8-Jan-61 9-Jan-61 Thankyou very much in advance Eliza [[alternative HTML version deleted]]