不同的清单方式 [英] Different ways of clearing lists

问题描述

当您想在 Python 中清除列表时，是否有任何理由执行比这两行中的任何一行更复杂的操作?

old_list = []old_list = 列表()

我问的原因是我刚刚在一些正在运行的代码中看到了这一点:

del old_list[ 0:len(old_list) ]

解决方案

就地清除列表将影响同一列表的所有其他引用.

例如，此方法不会影响其他引用:

<预><代码>>>>a = [1, 2, 3]>>>乙 = 一>>>a = []>>>打印(一)[]>>>打印(b)[1, 2, 3]

但是这个可以:

<预><代码>>>>a = [1, 2, 3]>>>乙 = 一>>>del a[:] # 等价于 del a[0:len(a)]>>>打印(一)[]>>>打印(b)[]>>>a 是 b真的

你也可以这样做:

<预><代码>>>>[:] = []

Is there any reason to do anything more complicated than one of these two lines when you want to clear a list in Python?

old_list = []
old_list = list()

The reason I ask is that I just saw this in some running code:

del old_list[ 0:len(old_list) ]

解决方案

Clearing a list in place will affect all other references of the same list.

For example, this method doesn't affect other references:

>>> a = [1, 2, 3]
>>> b = a
>>> a = []
>>> print(a)
[]
>>> print(b)
[1, 2, 3]

But this one does:

>>> a = [1, 2, 3]
>>> b = a
>>> del a[:]      # equivalent to   del a[0:len(a)]
>>> print(a)
[]
>>> print(b)
[]
>>> a is b
True

You could also do:

>>> a[:] = []

这篇关于不同的清单方式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！