python - Is there a way to write these ifs nicer?

Question

I need to write these four ifs in Python. Notice what it does, is changing between four possible states in a loop: 1,0 -> 0,1 -> -1,0 -> 0,-1 and back to first.

if [dx, dy] == [1,0]:
    dx, dy = 0, 1
if [dx, dy] == 0, 1:
    dx, dy = -1, 0
if [dx, dy] == [-1, 0]
    dx, dy = 0, -1
if [dx, dy] == [0, -1]:
    dx, dy = 1, 0

Can anyone suggest me a better/nicer way to write this?

question from:https://stackoverflow.com/questions/9104770/is-there-a-way-to-write-these-ifs-nicer

Answer 1

dx, dy = -dy, dx

When in doubt, apply maths. ;)