python 深复制浅复制-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_43206271/article/details/128870661

文章通过Python代码展示了深复制和浅复制的区别。在浅复制中，d[1]指向d[0]的同一内存地址，改变其中一个会影响另一个。而通过`copy.deepcopy`进行深复制，d[1]则拥有独立的副本，修改不会互相影响。

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1、简单理解：深复制就是为新变量开辟了新空间，只复制内容，当原内容改变时，新内容不跟着变。

浅复制是只是指向原变量，原变量内容变化时，新内容跟着变。

d = defaultdict(dict)
for i in range(1,20):
d[0][i] = i

d[1] = d[0] #浅复制，不论是d[1]还是d[0]变化另一个也都会变

for i in range(20,25):
d[1][i] = i

print(d)

输出：

defaultdict(<class 'dict'>,{0: {1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19, 20: 20, 21: 21, 22: 22, 23: 23, 24: 24}, 
1: {1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19, 20: 20, 21: 21, 22: 22, 23: 23, 24: 24}})

2、不想让跟着变化：

import copy

d = defaultdict(dict)
for i in range(1,20):
d[0][i] = i

d[1] = copy.deepcopy(d[0])###这里是变化
for i in range(20,25):
d[1][i] = i

print(d)

输出：

defaultdict(<class 'dict'>, {0: {1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19, 20: 20, 21: 21, 22: 22, 23: 23, 24: 24}, 1: {1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19}})