Getting open close for each day of the week separately

Question

I'm trying to write down the open and close price of each day, namely I want to write it down day by day and hence that Monday will write down the open close for Monday into a var variable and Tuesday will write down the open close for Tuesday. I will then put these values into an array for each day, which I'm able to do, but I can't come up with a method to get this data efficiently. I've already tried various combinations with dayofweek, but I'm failing.