深浅拷贝

1 a = [[1,2],2,3]
2 b = a.copy()
3 b[0] = 5
4 print(b)
5 print(a)
6 输出：
7 [5, 2, 3]
8 [[1, 2], 2, 3]

b = a[:] # 相当于b = a.copy()

查看变量id 例如：

 1 a = 1
 2 print(id(a),a)
 3 b = a
 4 print(id(b),b)
 5 a = 2
 6 print(id(a),a)
 7 输出：
 8 10914496 1
 9 10914496 1
10 10914528 2

b = a 表示b获得a整体的地址，若给a整体赋值，那么a就会重新开辟一个内存空间例子：

 1 a = [[1,2,3],4,5]
 2 print(id(a),a)
 3 b = a
 4 print(id(b),b)
 5 a[2]=9
 6 print(id(a),a)
 7 print(id(b),b)
 8 输出：
 9 139798308770632 [[1, 2, 3], 4, 5]
10 139798308770632 [[1, 2, 3], 4, 5]
11 139798308770632 [[1, 2, 3], 4, 9]
12 139798308770632 [[1, 2, 3], 4, 9]

copy() 函数实例例如：

 1 a = [[1,2,3],4,5,6]
 2 b = a.copy()
 3 print(id(a))
 4 print(id(b))
 5 a[2]=9
 6 print(a,b)
 7 a[0][0] = 0
 8 print(a,b)
 9 输出：
10 140671481131848
11 140671481132104
12 [[1, 2, 3], 4, 9, 6] [[1, 2, 3], 4, 5, 6]
13 [[0, 2, 3], 4, 9, 6] [[0, 2, 3], 4, 5, 6]

浅拷贝应用：例子：

1 husband = ['小胖',123,[15000,9000]]
2 wife = husband.copy()
3 wife[0] = '小胖的老婆'
4 wife[1] = 456
5 husband[2][1] -= 3000
6 print(wife)
7 输出：
8 ['小胖的老婆', 456, [15000, 6000]]

import copy 里面的copy.copy() 相当于浅拷贝a.copy()，shallow浅，表面

deepcopy(a) 深拷贝，复制所有。所有的id地址例子

 1 import copy
 2 husband = ['小胖',123,[15000,9000]]
 3 wife = husband.copy()
 4 xiaosan = copy.deepcopy(husband)
 5 xiaosan[0] = '小三'
 6 xiaosan[1] = 333
 7 wife[0] = '小胖的老婆'
 8 wife[1] = 456
 9 husband[2][1] -= 3000
10 print(wife)
11 print(xiaosan)
12 输出：
13 ['小胖的老婆', 456, [15000, 6000]]
14 ['小三', 333, [15000, 9000]]

不会改变其他的