Python中浅拷贝的三种实现形式

1、打开电脑运行，输入‘cmd’进入命令行窗口，输入‘python’

2、定义a列表，通过工厂模式浅拷贝b列表,代码如下：

>>> a=[1,2,[1,2]]

>>> b=list(a)

>>> [x for x in a]

[1, 2, [1, 2]]

>>> [x for x in b]

[1, 2, [1, 2]]

>>> [id(x) for x in a]

[1575119888, 1575119920, 38676616]

>>> [id(x) for x in b]

[1575119888, 1575119920, 38676616]

>>>

3、通过赋值或切片方式：

>>> c = a   或 c=a[:]或c=[i for i in a]

>>> [id(x) for x in a]

[1575119888, 1575119920, 38676616]

>>> [id(x) for x in c]

[1575119888, 1575119920, 38676616]

>>>

4、通过copy函数，代码如下：

>>> import copy

>>> d = copy.copy(a)

>>> [id(x) for x in a]

[1575119888, 1575119920, 38676616]

>>> [id(x) for x in d]

[1575119888, 1575119920, 38676616]

>>>

5、以上就是三种浅拷贝的方法，增加一个嵌套列表中的元素，会影响两个。

>>> a[2].append(3)

>>> a

[1, 2, [1, 2, 3]]

>>> b

[1, 2, [1, 2, 3]]

>>>

6、改变外层列表只影响自己，代码如下：

>>> a.append(4)

>>> a

[1, 2, [1, 2, 3], 4]

>>> b

[1, 2, [1, 2, 3]]

>>>