Create random number within an annulus

Question

I am trying generate a random number that is within an annulus, i.e. we have a max and min radius. I tried doing:

while True:
    x=random.uniform(-maxR, max         


        

Answer 1

The method you're using should work pretty efficiently for a thick annulus (where r1 <<< r2). If you're dealing instead with a narrow annulus (r2 - r1 <<< r1), then you may want to use something like this instead:

r = random.uniform(r1, r2)
theta = random.uniform(0, 2 * PI)
x = r * math.sin(theta)
y = r * math.cos(theta)

Note that this gives mildly non-uniform results (there's a constant distribution of points per unit angle, not per unit area).