> dat = data.frame( + a = c(1, 2, 0, 1), + b = c(1, 1, 1, 2), + c = c(2, 2, 2, 2), + stringsAsFactors = FALSE + ) > > apply(dat, 2, table) $a 0 1 2 1 2 1 $b 1 2 3 1 $c 2 4