copy & deepcopy

 1 import copy
 2 
 3 字典參照列表結論，看是否有深層嵌套。
 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 字符串和元組等不可變數據類型，打死都不變
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 若是隻是copy的話，copy.copy() 針對外層依舊是深拷貝，但對內層來說就是淺拷貝了，會改變值。
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 深拷貝， 無論你是啥，只要copy.deepcopy()了。 無論你變不變，我變我是狗。