Hi, What is the most efficient method to calculate delta of columns? Consider this:
(key1, 1, 2, 3) (key1, 2, 4, 5) (key2, 1, 2, 4) (key1, 3, 6, 9) (key2, 2, 4, 6) The expected transformation output should look like this: (key1, 1, 2, 2) (key1, 1, 2, 4) (key2, 1, 2, 2) The idea is to group by f0, and compute f1 (current value) - f1 (previous value). How to write this in pig? if there is a underflow value, it should reset to 0, for example: (key1, 1, 2, 3) (key1, 0, 0, 0) (key1, 2, 3, 4) The output should be: (key1, 0, 0, 0) (key1, 2, 3, 4) I haven't been able to find a solution from google. Anyone? regards, Eric
