I would like to combine rows which have the same keys(multiple).
For example, If I have this kind of data:
OD, Itinerary, Passengers
AAA, I, 5
AAA, I, 6
AAA, II, 4
BBB, II, 3
And I would like to combine rows(by adding up "Passengers") whose first two columns are the same, like this:
OD, Itinerary, Passengers
AAA, I, 11
AAA, II, 4
BBB, II, 3
I have tried group_by and summarise. That will do but I wonder whether there is a simpler way to do that.