search for: mealacod

...s 300,000 rows), looping may not be the most efficient. The original question was: I would like to identify all customer?s ids who have had each meal combination in the first table so the final output would be the first table with ids attached next to each meal combination in each row like this: mealAcode mealBcode ids 1 34 39 11 2 25 34 15 11 3 25 77 15 85 M <- structure(list(mealAcode = c(34L, 89L, 25L, 34L, 25L), mealBcode = c(66L, 39L, 77L, 39L, 34L)), .Names = c("mealAcode", "mealBcode"), row...