> which( !is.na(p), arr.ind=TRUE) row col [1,] 1 2 [2,] 1 3 [3,] 2 4 [4,] 4 5 [5,] 2 7
lapply(apply(p, 1, function(x) which(!is.na(x)) ) , paste, collapse=", ")
> apply(p, 1, function(x) which(!is.na(x)) ) [[1]] [1] 2 3 [[2]] [1] 4 7 [[3]] integer(0) [[4]] [1] 5 [[5]] integer(0)
which( !is.na(p), arr.ind=TRUE)