如何复制字典，只编辑副本 [英] How to copy a dictionary and only edit the copy

问题描述

有人可以向我解释一下吗？这对我来说没有任何意义。

我将字典复制到另一个字体，并编辑第二个字符，两者都被更改。为什么会发生这种情况？

 >>> dict1 = {key1：value1，key2：value2} 
>>> dict2 = dict1 
>>> dict2 
 {'key2'：'value2'，'key1'：'value1'} 
>>> dict2 [key2] =为什么？ 
>>> dict1 
 {'key2'：'WHY ?!'，'key1'：'value1'} 
  

解决方案

Python 永不隐式复制对象。当您设置 dict2 = dict1 时，您将使它们引用相同的精确的dict对象，因此当您更改它时，对其进行的所有引用将保持引用当前的对象状态。

如果要复制dict（这是罕见的），您必须明确地使用

  dict2 = dict（dict1）
  

或

  dict2 = dict1.copy（）
  

Can someone please explain this to me? This doesn't make any sense to me.

I copy a dictionary into another and edit the second and both are changed. Why is this happening?

>>> dict1 = {"key1": "value1", "key2": "value2"}
>>> dict2 = dict1
>>> dict2
{'key2': 'value2', 'key1': 'value1'}
>>> dict2["key2"] = "WHY?!"
>>> dict1
{'key2': 'WHY?!', 'key1': 'value1'}

解决方案

Python never implicitly copies objects. When you set dict2 = dict1, you are making them refer to the same exact dict object, so when you mutate it, all references to it keep referring to the object in its current state.

If you want to copy the dict (which is rare), you have to do so explicitly with

dict2 = dict(dict1)

or

dict2 = dict1.copy()

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