Python打印数组的顺序

Question

从以下数组中我如何得到所述的输出

arr=["harry","sally","tom"]

harry
harry
harry
sally
sally
tom

sally
sally
sally
tom
tom
harry

tom
tom
tom
harry
harry
sally

我尝试了什么

>>> for i in range(len(arr)):
...     print arr[i] * 3
...     print arr[i+1]*2
...     print arr[i-1] 
... 

Traceback (most recent call last):
File "<stdin>", line 3, in <module>
IndexError: list index out of range

Answer 1

使用模数运算符环绕列表的开头，或者将列表加倍，但使用原始的长度。

Answer 2

>>> for i in range(len(arr)):
        print arr[i % len(arr)] * 3
        print arr[(i+1) % len(arr)] * 2
        print arr[(i+2) % len(arr)] * 1