Back and forth loop Python
Use the chain method of itertools
import itertoolsfor i in range(0, infinity): for j in itertools.chain(range(0, 100, 1), range(100, 0, -1)): print(j) # (in my case 100 lines of code)As suggested by @Chepner, you can use itertools.cycle() for the infinite loop:
from itertools import cycle, chainfor i in cycle(chain(range(0, 100, 1), range(100, 0, -1))): ....
As well as the other answers you can use a bit of maths:
while(True): for i in range(200): if i > 100: i = 200 - i
Here's yet another possibility:
while notConverged: for i in xrange(-100, 101): print 100 - abs(i)