mylist = list()与mylist = []在Python中 [英] mylist = list() vs mylist = [] in Python

问题描述

可能重复:
在Python中创建列表-偷偷摸摸地进行着吗?
在Python中创建空列表

Possible Duplicate:
Creating a list in Python- something sneaky going on?
Creating an empty list in Python

请考虑以下内容:

mylist = list()

和:

mylist = []

使用list()或[]是否有任何好处-在某些情况下应优先使用另一个?

Is there any benefit to using list() or [] - should one be used over the other in certain situation?

推荐答案

对于空列表，建议使用[].这将更快，因为它避免了对内置名称list的名称查找.内置名称也可以用全局或本地名称覆盖；这只会影响list()，而不会影响[].

For an empty list, I'd recommend using []. This will be faster, since it avoids the name look-up for the built-in name list. The built-in name could also be overwritten by a global or local name; this would only affect list(), not [].

内置的list()对于将其他可迭代对象转换为列表很有用，

The list() built-in is useful to convert some other iterable to a list, though:

a = (1, 2, 3)
b = list(a)

为完整起见，我的机器上空列表的两个选项(Python 2.7.3rc2，Intel Core 2 Duo)的计时:

For completeness, the timings for the two options for empty lists on my machine (Python 2.7.3rc2, Intel Core 2 Duo):

In [1]: %timeit []
10000000 loops, best of 3: 35 ns per loop

In [2]: %timeit list()
10000000 loops, best of 3: 145 ns per loop

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