Dear list I am trying to count the no of occurances in a column of a data frame and there is missing data identifed by NA. I am able to melt and cast the data correctly as well as sum the occurances using margins and sum. Here are the melt and cast commands bw = melt(res, id=c("lab","r"), "pf_zbw") b = cast(bw, lab ~ r, sum, margins = T) Sample Data (before using sum and margins) lab 1 2 3 4 5 6 1 4er66 1 NA 1 0 NA 0 2 4gcyi 0 0 1 0 0 0 3 5d3hh 0 0 0 NA 0 0 4 5d3wt 0 0 0 0 0 0 . . lines deleted to save space . 69 v3st5 NA NA 1 NA NA NA 70 a22g5 NA 0 NA NA NA NA 71 b5dd3 NA 0 NA NA NA NA 72 g44d2 NA 0 NA NA NA NA Data after using sum and margins lab 1 2 3 4 5 6 (all) 1 4er66 1 0 1 0 0 0 2 2 4gcyi 0 0 1 0 0 0 1 3 5d3hh 0 0 0 0 0 0 0 4 5d3wt 0 0 0 0 0 0 0 5 6n44r 0 0 0 0 0 0 0 . .lines deleted to save space . 70 a22g5 0 0 0 0 0 0 0 71 b5dd3 0 0 0 0 0 0 0 72 g44d2 0 0 0 0 0 0 0 73 (all) 5 2 4 3 5 7 26 Uisng length just tells me how many total rows there are. What I need to do is count how many rows there is valid data, in this case either a one (1) or a zero (0) in b I have a report to construct for tomorrow Mon so any help would be appreciated Regards Steve [[alternative HTML version deleted]]