Question

I am trying to write this loop in Python but get confused. Basically I have a starting angle 90 that I want to use a range of -90 to 90, iterating 10 times. After the loop is done, I want to divide the angle by half and repeat the process of using -45 to 45, by 10 iterations, etc.

The end values must be included, so 90 is the last value for the first loop, then 45 is the last value for the second loops, etc.

How can I write this elegantly and efficiently in Python?

startAngle = 90
for i in range(5):
    for x in range(10):
        print values from -startAngle to startAngle (startAngle included)
    startAngle = startAngle / 2

Answer 1

def angles(x):
    return [ i * x / 5 - x for i in xrange(11)]

angles(90) returns [-90, -72, -54, -36, -18, 0, 18, 36, 54, 72, 90]

angles(45) returns [-45, -36, -27, -18, -9, 0, 9, 18, 27, 36, 45]

You can now iterate over the return value, it is a list.

There are ten steps in my angles method returning eleven values.

If you want another number of steps:

def angles(angle, steps):
    return [ i * angle * 2 / (steps - 1) - angle for i in xrange(steps)]

angles(90, 5) returns [-90, -45, 0, 45, 90]