How would I shift one value to other depending on angle?

Lets say I have two values. a = 1.5 b = 3 I want to shift value "a" to value "b" using camera Y angle. Yangle(360) = a when Yangle(180) = b I've figured out how to find camera Y angle, but still haven't got how to use Yangle in order to shift between values, for now I only used simple math.

value = AngleY/180

it works quiet well, changing Y angle into 1 if Y angle is 0 or 2 if 360, but it only shifts between 1 and 2 counter clockwise, when I need it clockwise (or I want 90 to be 1 and 180 to be 2 as example), how could I acomplish that?