I have a timeseries:
Sales
2018-01-01 66.65
2018-01-02 66.68
2018-01-03 65.87
2018-01-04 66.79
2018-01-05 67.97
2018-01-06 96.92
2018-01-07 96.90
2018-01-08 96.90
2018-01-09 96.38
2018-01-10 95.57
Given an arbitrary sequence of values, let's say [66.79,67.97,96.92,96.90], how could I obtain the corresponding indices, for example: [2018-01-04, 2018-01-05,2018-01-06,2018-01-07]?