In a Pandas Series there are multiple rows with the same date. I want to sum the values in those rows and join them into a single row, like below:
dates dates
2019-01-03 1 2019-01-03 1
2019-01-04 2 2019-01-04 9
2019-01-04 3 2019-01-08 -11
2019-01-04 4 -------> 2019-01-09 -6
2019-01-08 -5
2019-01-08 -6
2019-01-09 -6
Note! In the example above, there are 3 rows with the same date "2019-01-04", and two rows with "2019-01-08". Each has been collapsed to a single row, with their sum.
How can I achieve this?
