如何将功能应用于列表的元素？ [英] How to apply function to elements of a list?

问题描述

我想对列表中的所有元素应用一个函数，但我想实际更改元素（哪些是对象），而不是查看结果。我认为这是使用 map（）或列表推导的问题。

I want to apply a function to all elements in the list, but I want to actually change the elements (which are objects), not view results. I think this is the problem with using map() or list comprehensions.

class Thing(object):
    pass

# some collection of things
my_things

# they are all big...

# produces SyntaxError: invalid syntax
[i.size = "big" for i in my_things]

# produces SyntaxError: lambda cannot contain assignment
map(lambda i: i.size="big", [i for i in my_things]) 

# no error, but is it the preferred way?
for i in my_things:
    i.size="big"

什么是这样做吗？

推荐答案

for i in my_things:
    i.size = "big"

您不想既不使用 map 也不使用列表comprehansion，因为它们实际上创建了新的列表。你不需要这个开销，是吗？

You don't want to use neither map nor list comprehansion because they actually create new lists. And you don't need that overhead, do you?

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