来回循环Python

Question

我想创建一个无限循环,从0到100向上计数到0到0(依此类推),只有在满足循环内的某些收敛标准时才会停止,所以基本上是这样的:

for i in range(0, infinity):
    for j in range(0, 100, 1):
        print(j) # (in my case 100 lines of code)
    for j in range(100, 0, -1):
        print(j) # (same 100 lines of code as above)

有没有办法将两个for循环合并到一个j中,以便我没有在循环中写出两次相同的代码？

Answer 1

使用chain方法itertools

import itertools
for 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)

正如@Chepner所建议的那样,你可以使用itertools.cycle()无限循环:

from itertools import cycle, chain

for i in cycle(chain(range(0, 100, 1), range(100, 0, -1))):
    ....

Answer 2

除了其他答案,你可以使用一些数学:

while(True):
    for i in range(200):
        if i > 100:
            i = 200 - i

Answer 3

这是另一种可能性:

while notConverged:
    for i in xrange(-100, 101):
        print 100 - abs(i)

Answer 4

如果您有一组重复的代码,请使用函数来节省空间和精力:

def function(x, y, x, num_from_for_loop):
    # 100 lines of code 

while not condition:
    for i in range(1, 101):
        if condition:
            break
        function(x, y, z, i)
    for i in range(100, 0, -1):
        if condition:
            break
        function(x, y, z, i)

你甚至可以用一个 while True