Transform data van $0^\circ$ to $360^\circ$ towards $-180^\circ$ to $180^\circ$

Question

I have some data from a glacier surface, for which the aspect ranges from $0^\circ$ (N) to $90^\circ$ (E) to $180^\circ$ (S) to $270^\circ$ (W) to $360^\circ$ (again N). I want to transform these data so that $180^\circ$ (N) to $90^\circ$ (E) to $0^\circ$ (S) to $-90^\circ$ (W) to $-180^\circ$ (N again).

How can I do this?

Thanks

Answer 1

If your original angle is $A$, then your new angle $B = 180 - A$ (in degrees).

Plug in the angles to verify.