python字典副本

Python never implicitly copies the dictionary or any objects. So, while we set dict2 = dict1, we're making them refer to the same dictionary object. Hence, even when we mutate the dictionary, all the references made to it, keep referring to the object in its current state.

Python绝不会隐式复制字典或任何对象。 因此，当我们设置dict2 = dict1时 ，我们使它们引用相同的字典对象。 因此，即使我们对字典进行了变异，对其的所有引用也会继续引用该对象的当前状态。

dict1 = {"key1": "abc", "key2": "efg"}
dict2 = dict1
print(dict1)
print(dict2)
dict2['key2'] = 'pqr'
print(dict1)
print(dict2)

Output

输出量

{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'pqr'}
{'key1': 'abc', 'key2': 'pqr'}

To copy a dictionary, either uses a shallow copy or deep copy approach, as explained in the below example.

要复制字典 ，请使用浅层复制或深层复制方法 ，如以下示例中所述。

使用浅拷贝 (Using shallow copy)

dict1 = {"key1": "abc", "key2": "efg"}
print(dict1)
dict3 = dict1.copy()
print(dict3)
dict3['key2'] = 'xyz'
print(dict1)
print(dict3)

Output

输出量

{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'xyz'}

使用深度复制 (Using deep copy)

import copy
dict1 = {"key1": "abc", "key2": "efg"}
print(dict1)
dict4 = copy.deepcopy(dict1)
print(dict4)
dict4['key2'] = 'test1'
print(dict4)
print(dict1)

Output

输出量

{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'efg'}
{'key1': 'abc', 'key2': 'test1'}
{'key1': 'abc', 'key2': 'efg'}

翻译自: https://www.includehelp.com/python/how-to-copy-a-dictionary-and-only-edit-the-copy.aspx

python字典副本