python range() in for loop maximum

Question

How do I specify a maximum in the range function to that it reverts back to the beginning after a certain number?

ie:

for i in range(253, 2):
    print i

Would print 253, 254, 255, 0 , 1, 2  

If the maximum was 255

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Edit (after reading comments and answers)

This should work right?

if start < end:
    list = [ i for i in range(start, end + 1 ) ]
else:
    list = [ i % 256 for i in range(start, end + 256 + 1 ) ]

Looking back at this, people seem to love complexity over simplicity. Why use itertools and other complicated constructs when it can be done with a simple loop?

Answer 1

You want to use modular arithmetic (or clock arithmetic). https://en.wikipedia.org/wiki/Modular_arithmetic

If you want to print 253, 254, 255, 0, 1, ..., 252 , you can use the following code.

for i in range(0, 256):
    print((253+i)%256)

Answer 2

If I understood well, it's not exactly a range issue.

Given 2 numbers min and max :

• if min < max , you want the list of numbers between min and max
• else you want the list from min to 255 and 0 to max

It's only pseudo-code, but it might be enough to get you started to solve your problem (using one or two range calls)

Answer 3

There is some issues with the way you specify the range. But you could do something like this:

max_val = 255
for i in range(253, max_val+2):
    print i%max_val

But since range is specified with the end value not included you would need to do range(253, (max_val+1)+2) if you want the 2 to be printed.

If you beforehand do not know if the range-end value will be more or less than the range-start you could do

start = 253
end = 2 # +1 if you want the 2 to be printed
for i in range(start, end+(start>end and max_val or 0)):
    print i%max_val

Answer 4

Split it into two ranges: range1 = range(start, highest+1) and range2 = range(end) . Then using itertools, you can:

for i in it.chain(range1, range2):