用python中的列表替换元素 [英] Replace element with a list in python

问题描述

在python中，用另一个列表中的元素替换列表中的元素的最佳方法是什么?

In python, what is the best way to replace an element in a list with the elements from another list?

例如，我有:

a = [ 1, 'replace_this', 4 ]

我想用[2, 3]替换replace_this.更换后必须是:

I want to replace replace_this with [2, 3]. After replacing it must be:

a = [ 1, 2, 3, 4 ]

更新

当然可以进行切片(很抱歉，我没有在问题中写它)，但是问题是您可能有多个replace_this值列表.在这种情况下，您需要循环进行替换，这将变得不理想.

Of course, it is possible to do with slicing (I'm sorry that I didn't write it in the question), but the problem is that it is possible that you have more than one replace_this value in the list. In this case you need to do the replacement in a loop and this becomes unoptimal.

我认为使用itertools.chain会更好，但我不确定.

I think that it would be better to use itertools.chain, but I'm not sure.

推荐答案

您可以使用切片:

>>> a = [ 1, 'replace_this', 4 ]
>>> a[1:2] = [2, 3]
>>> a
[1, 2, 3, 4]

正如@mgilson所指出的-如果您不知道要替换的元素的位置，则可以使用a.index来查找它...(请参阅他的评论)

And as @mgilson points out - if you don't happen to know the position of the element to replace, then you can use a.index to find it... (see his comment)

与不使用切片有关的更新

使用itertools.chain，确保replacements具有可迭代项:

Using itertools.chain, making sure that replacements has iterables:

from itertools import chain

replacements = {
    'replace_this': [2, 3],
    4: [7, 8, 9]
}

a = [ 1, 'replace_this', 4 ]
print list(chain.from_iterable(replacements.get(el, [el]) for el in a))
# [1, 2, 3, 7, 8, 9]

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