copy & deepcopy

 1 import copy
 2
 3 字典参照列表结论，看是否有深层嵌套。
 4 a = {'name':1,'age':2}
 5 b = a
 6 a['name'] = 'ff'
 7 print(a)
 8 print(b)
 9 print(id(a),id(b))
10
11
12 a = {'name':1,'age':2}
13 b = copy.deepcopy(a)
14 a['name'] = 'ff'
15 print(a)
16 print(b)
17 print(id(a),id(b))
18 """
19 {'name': 'ff', 'age': 2}
20 {'name': 'ff', 'age': 2}
21 4301093048 4301093048
22 {'name': 'ff', 'age': 2}
23 {'name': 1, 'age': 2}
24 4301093120 4302783256
25 """
26
27 字符串和元组等不可变数据类型，打死都不变
28 a = 'ff'
29 b = a
30 a = 'ff1'
31 print(a,b) # ff1 ff
32
33 a = 'ff'
34 b = copy.copy(a)
35 a = 'ff1'
36 print(a,b) # ff1 ff
37
38 a = 'ff'
39 b = copy.deepcopy(a)
40 a = 'ff1'
41 print(a,b) # ff1 ff
42
43 a = [1,2,3]
44 b = [4,5,6]
45 c = [a,b]
46 d = c
47 print(id(c),id(d)) # 4322641352 4322641352
48 c.append(9)
49 print(c)   # [[1, 2, 3], [4, 5, 6], 9]
50 print(d)   # [[1, 2, 3], [4, 5, 6], 9]
51 print(id(c),id(d)) # 4322641352 4322641352
52
53 d = copy.copy(c)
54 c.append(9)
55 print(c) # [[1, 2, 3], [4, 5, 6], 9]
56 print(d) # [[1, 2, 3], [4, 5, 6]]
57 c[0].append(8)
58 print(c) # [[1, 2, 3, 8], [4, 5, 6]]
59 print(d) # [[1, 2, 3, 8], [4, 5, 6]]
60 如果只是copy的话，copy.copy() 针对外层依旧是深拷贝，但对内层来讲就是浅拷贝了，会改变值。
61
62
63 d = copy.deepcopy(c)
64 c.append(9)
65 print(c) # [[1, 2, 3], [4, 5, 6], 9]
66 print(d) # [[1, 2, 3], [4, 5, 6]]
67 c[0].append(8)
68 print(c)  # [[1, 2, 3, 8], [4, 5, 6]]
69 print(d)  # [[1, 2, 3], [4, 5, 6]]
70 深拷贝， 不管你是啥，只要copy.deepcopy()了。 不管你变不变，我变我是狗。