python list index negative
Python lists can be "back indexed" using negative indices. -1 signifies the last element, -2 signifies the second to last and so on. It just so happens that in your list of length 2, the last element is also the element at index 1 . Your book s,The solution proposed by you can be derived directly from the definition of negative index: python implicitly add len(list) to passed negative index. So, it's fine. But it's a bit strange that you need to find negative index. I think this task is
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 python list index negative 相關參考資料
how do I create a python list with a negative index - Stack Overflow
Additionally, you are attempting to write to a list at indices of it that don't already exist (never mind the fact that you want them to be negative - negative indices have a special meaning in P... https://stackoverflow.com list - Negative indexing in Python - Stack Overflow
Python lists can be "back indexed" using negative indices. -1 signifies the last element, -2 signifies the second to last and so on. It just so happens that in your list of length 2, the la... https://stackoverflow.com Negative list index in python - Stack Overflow
The solution proposed by you can be derived directly from the definition of negative index: python implicitly add len(list) to passed negative index. So, it's fine. But it's a bit strange that... https://stackoverflow.com python - List without negative indexing - Stack Overflow
Although I pointed out my reluctance in the comments, I'll play your game. class PositiveList(list): def __getitem__(self, ind): if ind < 0: raise IndexError("Expected a positive index, i... https://stackoverflow.com python - Negative list index? - Stack Overflow
Negative numbers mean that you count from the right instead of the left. So, list[-1] refers to the last element, list[-2] is the second-last, and so on. https://stackoverflow.com Python Lists – Negative Indexing, Slicing, Stepping, Comparing, Max ...
Python Lists – Negative Indexing, Slicing, Stepping, Comparing, Max and Min. Welcome to the second part of lists. In the last chapter you learnt about basic functions of lists. In this chapter we lear... http://knowledgehills.com Python, negative values aren't out of range in list - Stack Overflow
a = [1, 2, 3, 4] >>> a[-1] 4 >>> a[-2] 3 >>> a[-3] 2 >>> a[-4] 1 >>> # This blows up because there is no item that is >>> # 5 positions from the ... https://stackoverflow.com Why does Python return negative list indexes? - Stack Overflow
In Python, negative list indices indicate items counted from the right of the list (that is, l[-n] is shorthand for l[len(l)-n] ). If you find you need negative indices to indicate an error, then you... https://stackoverflow.com |