copy&deepcopy

 import copy

 字典参照列表结论，看是否有深层嵌套。
 a = {'name':1,'age':2}
 b = a
 a['name'] = 'ff'
 print(a)
 print(b)
 print(id(a),id(b))

 a = {'name':1,'age':2}
 b = copy.deepcopy(a)
 a['name'] = 'ff'
 print(a)
 print(b)
 print(id(a),id(b))
 """
 {'name': 'ff', 'age': 2}
 {'name': 'ff', 'age': 2}
 4301093048 4301093048
 {'name': 'ff', 'age': 2}
 {'name': 1, 'age': 2}
 4301093120 4302783256
 """

 字符串和元组等不可变数据类型，打死都不变
 a = 'ff'
 b = a
 a = 'ff1'
 print(a,b) # ff1 ff

 a = 'ff'
 b = copy.copy(a)
 a = 'ff1'
 print(a,b) # ff1 ff

 a = 'ff'
 b = copy.deepcopy(a)
 a = 'ff1'
 print(a,b) # ff1 ff 

 a = [1,2,3]
 b = [4,5,6]
 c = [a,b]
 d = c
 print(id(c),id(d)) # 4322641352 4322641352
 c.append(9)
 print(c)   # [[1, 2, 3], [4, 5, 6], 9]
 print(d)   # [[1, 2, 3], [4, 5, 6], 9]
 print(id(c),id(d)) # 4322641352 4322641352

 d = copy.copy(c)
 c.append(9)
 print(c) # [[1, 2, 3], [4, 5, 6], 9]
 print(d) # [[1, 2, 3], [4, 5, 6]]
 c[0].append(8)
 print(c) # [[1, 2, 3, 8], [4, 5, 6]]
 print(d) # [[1, 2, 3, 8], [4, 5, 6]]
 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。

 d = copy.deepcopy(c)
 c.append(9)
 print(c) # [[1, 2, 3], [4, 5, 6], 9]
 print(d) # [[1, 2, 3], [4, 5, 6]]
 c[0].append(8)
 print(c)  # [[1, 2, 3, 8], [4, 5, 6]]
 print(d)  # [[1, 2, 3], [4, 5, 6]]
 深拷贝， 不管你是啥，只要copy.deepcopy()了。 不管你变不变，我变我是狗。

copy&deepcopy