1. 浅拷贝
- 浅拷贝是对于一个对象的顶层拷贝
通俗的理解是：拷贝了引用，并没有拷贝内容
2. 深拷贝
深拷贝是对于一个对象所有层次的拷贝(递归)
进一步理解拷贝
In [23]: a = [11,22,33] In [24]: b = [44,55,66] In [25]: c = (a,b) In [26]: e = copy.deepcopy(c) In [27]: a.append(77) In [28]: a Out[28]: [11, 22, 33, 77] In [29]: b Out[29]: [44, 55, 66] In [30]: c Out[30]: ([11, 22, 33, 77], [44, 55, 66]) In [31]: e Out[31]: ([11, 22, 33], [44, 55, 66]) In [32]: In [32]: In [32]: f = copy.copy(c) In [33]: a.append(88) In [34]: a Out[34]: [11, 22, 33, 77, 88] In [35]: b Out[35]: [44, 55, 66] In [36]: c Out[36]: ([11, 22, 33, 77, 88], [44, 55, 66]) In [37]: e Out[37]: ([11, 22, 33], [44, 55, 66]) In [38]: f Out[38]: ([11, 22, 33, 77, 88], [44, 55, 66])
3. 拷贝的其他方式
浅拷贝对不可变类型和可变类型的copy不同
In [88]: a = [11,22,33] In [89]: b = copy.copy(a) In [90]: id(a) Out[90]: 59275144 In [91]: id(b) Out[91]: 59525600 In [92]: a.append(44) In [93]: a Out[93]: [11, 22, 33, 44] In [94]: b Out[94]: [11, 22, 33] In [95]: In [95]: In [95]: a = (11,22,33) In [96]: b = copy.copy(a) In [97]: id(a) Out[97]: 58890680 In [98]: id(b) Out[98]: 58890680
分片表达式可以赋值一个序列:
a = "abc" b = a[:]
字典的copy方法可以拷贝一个字典
d = dict(name="zhangsan", age=27) co = d.copy()
有些内置函数可以生成拷贝(list)
a = list(range(10)) b = list(a)
copy模块中的copy函数
import copy a = (1,2,3) b = copy.copy(a)
