pop() 列表中的中间两个元素

Question

刚刚回顾了我的 Python 课程，发现我忘记了如何做到这一点。

def outsideIn2(lst):

'''(list)->list

Returns a new list where the middle two elements have been
removed and placed at the beginning of the result. Assume all lists are an even
length

>>> outsideIn2(['C','a','r','t','o','n']) 
['r','t','C','a','o','n'] # rt moves to front
>>> outsideIn2(['H','i']) 
['H','i'] # Hi moves to front so output remains the same.
>>> outsideIn2(['B','a','r','b','a','r','a',' ','A','n','n','e']) 
['r','a','B','a','r','b,','a',' ','A','n','n','e'] # ra moves to front.
'''
length = len(lst)
middle1 = lst.pop((len(lst) / 2) - 1)
middle2 = lst.pop((len(lst) / 2) + 1)

lst.insert([0], middle1)
lst.insert([1], middle2)                  

return lst

我收到此错误：

middle1 = lst.pop((len(lst) / 2) - 1)

类型错误：需要整数参数，但得到了浮点数

我究竟做错了什么？

Answer 1

当您升级到 Python 3 时，“ /”运算符从整数除法更改为实数除法。切换到 ' //' 运算符。