循环选择列表的元素

Question

我有一个如下所示的列表

list1 = [cont1，cont2，cont4，cont5]

如何在python中实现循环逻辑来选择列表的元素， 每次我尝试访问元素

Answer 1

我建议使用itertools.cycle。

  

使迭代器从iterable返回元素并保存a   每个的副本。当iterable耗尽时，返回from中的元素   保存副本。无限期地重复。

样本用法：

seq = [1,2,3,4]
round_robin = itertools.cycle(seq)

assert round_robin.next() == 1
assert round_robin.next() == 2
assert round_robin.next() == 3
assert round_robin.next() == 4
assert round_robin.next() == 1
assert round_robin.next() == 2
assert round_robin.next() == 3
assert round_robin.next() == 4

Answer 2

seq = [1,2,3,4]
n = -1
def round_rob_seq():
  global n
  n = n + 1
  return seq[n % len(seq)]

or

def round_rob_seq():
  global n
  n = n + 1
  if n == len(seq):
     n = 0
  return seq[n]