My data is intraday stock prices data, multiple days. This is a simplified version:
Last
2015-01-02 08:30:00 2035.00
2015-01-02 10:30:00 2038.25
2015-01-02 15:15:00 2025.25
2015-01-05 08:30:00 2020.25
2015-01-05 10:30:00 2010.75
2015-01-05 15:15:00 2015.00
2015-01-06 08:30:00 1988.00
2015-01-06 10:30:00 1990.25
2015-01-06 15:15:00 1970.00
Given that in the data, every day, the last row is at 15:15:00, how can I take the difference (15:15:00 Row - Last), for every row per day. Here's the desired output.
Last Dif
2015-01-02 08:30:00 2035.25 -10
2015-01-02 10:30:00 2038.25 -13
2015-01-02 15:15:00 2025.25 0
2015-01-05 08:30:00 2020.25 -5.25
2015-01-05 10:30:00 2010.00 5
2015-01-05 15:15:00 2015.00 0
2015-01-06 08:30:00 1988.00 -18
2015-01-06 10:30:00 1990.25 -20.25
2015-01-06 15:15:00 1970.00 0