I've a problem with the ore matrix. When I tried that all is OK with apply function : ORE> tab1 <- as.matrix(matrix(rep(seq(5), 5), ncol = 5)) ORE> apply(tab1,1, sum) [1] 5 10 15 20 25 …

The apply function is not overloaded for ore.frame objects. The rowSums function is overloaded for ore.frames, and will produce the results you need: R> rowSums(tab2) [1] 5 10 15 20 25 Sherry…