连接两个列表 - '+=' 和 extend() 之间的区别 [英] Concatenating two lists - difference between '+=' and extend()

问题描述

我已经看到实际上有两种(可能更多)在 Python 中连接列表的方法:一种方法是使用 extend() 方法:

I've seen there are actually two (maybe more) ways to concatenate lists in Python: One way is to use the extend() method:

a = [1, 2]
b = [2, 3]
b.extend(a)

另一个使用加号(+)运算符:

the other to use the plus(+) operator:

b += a

现在我想知道:这两个选项中的哪一个是进行列表连接的pythonic"方式，两者之间是否有区别(我查阅了官方 Python 教程，但找不到任何关于此主题的信息).

Now I wonder: Which of those two options is the 'pythonic' way to do list concatenation and is there a difference between the two (I've looked up the official Python tutorial but couldn't find anything anything about this topic).

推荐答案

字节码级别的唯一区别是 .extend 方式涉及到函数调用，这在 Python 中比 INPLACE_ADD.

The only difference on a bytecode level is that the .extend way involves a function call, which is slightly more expensive in Python than the INPLACE_ADD.

除非您执行此操作数十亿次，否则您无需担心.然而，瓶颈很可能位于其他地方.

It's really nothing you should be worrying about, unless you're performing this operation billions of times. It is likely, however, that the bottleneck would lie some place else.

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