A similar question might have been asked before, but I couldn't find the exact one fitting to my problem. I want to group by a dataframe based on two columns. For exmaple to make this
id product quantity
1 A 2
1 A 3
1 B 2
2 A 1
2 B 1
3 B 2
3 B 1
Into this:
id product quantity
1 A 5
1 B 2
2 A 1
2 B 1
3 B 3
Meaning that summation on "quantity" column for same "id" and same "product".