Get value from chart with another condition on other field

[#1]

Hello Expert,

Say we have such data:

Date     Time      Price

1/1        09:00    1

1/1        10:00    2

1/2        09:00    3

1/2         10:00   4

The goal is to display the initial price per day in one line chart, where the price is based on the minmium time of the day.

Say, the initial price of 1/1 is 1 and 3 for 1/2.

One more step, the initial price is the price based on maxmium time of previous day.

How to get there for both options?

Many thanks

HTC