Python 3 范围与 Python 2 范围
问题描述
我最近开始学习python 3.
在 python 2 中，range() 函数可用于分配列表元素:
I recently started learning python 3.
In python 2 the range() function can be used to assign list elements:
>>> A = []
>>> A = range(0,6)
>>> print A
[0, 1, 2, 3, 4, 5]
但在 python 3 中，range() 函数输出如下:
But in python 3 the range() function outputs this:
>>> A = []
>>> A = range(0,6)
>>> print(A)
range(0, 6)
为什么会这样?
为什么python会做这个改变?
是福还是祸?
Why is this happening?
Why did python do this change?
Is it a boon or a bane?
解决方案
Python 3 在 python 2 的很多地方使用 迭代器使用 lists.docs 给出了详细的解释，包括更改为 range.
Python 3 uses iterators for a lot of things where python 2 used lists.The docs give a detailed explanation including the change to range.
优点是如果您使用大范围迭代器或映射，Python 3 不需要分配内存.例如
The advantage is that Python 3 doesn't need to allocate the memory if you're using a large range iterator or mapping. For example
for i in range(1000000000): print(i)
在 python 3 中需要更少的内存.如果您确实希望 Python 一次将列表全部展开，您可以
requires a lot less memory in python 3. If you do happen to want Python to expand out the list all at once you can
list_of_range = list(range(10))
相关文章