对于不可变对象，创建副本没有多大意义，因为它们不会改变。对于可变对象^{}，^{}和^{}的行为不同。让我们用例子来讨论它们。

赋值操作只是将源的引用赋值给目标，例如：>>> i = [1,2,3]

>>> j=i

>>> hex(id(i)), hex(id(j))

>>> ('0x10296f908', '0x10296f908') #Both addresses are identical

现在i和j在技术上指的是同一个列表。i和j都有相同的内存地址。任何更新

它们中的一个会反射到另一个。e、 克：>>> i.append(4)

>>> j

>>> [1,2,3,4] #Destination is updated

>>> j.append(5)

>>> i

>>> [1,2,3,4,5] #Source is updated

另一方面，copy和deepcopy创建变量的新副本。所以现在对原始变量的更改将不会反映出来

复制变量，反之亦然。但是copy(shallow copy)，不要创建嵌套对象的副本，而只是

复制嵌套对象的引用。Deepcopy递归地复制所有嵌套对象。

演示copy和deepcopy行为的一些示例：

使用copy：的平面列表示例>>> import copy

>>> i = [1,2,3]

>>> j = copy.copy(i)

>>> hex(id(i)), hex(id(j))

>>> ('0x102b9b7c8', '0x102971cc8') #Both addresses are different

>>> i.append(4)

>>> j

>>> [1,2,3] #Updation of original list didn't affected copied variable

使用copy：的嵌套列表示例>>> import copy

>>> i = [1,2,3,[4,5]]

>>> j = copy.copy(i)

>>> hex(id(i)), hex(id(j))

>>> ('0x102b9b7c8', '0x102971cc8') #Both addresses are still different

>>> hex(id(i[3])), hex(id(j[3]))

>>> ('0x10296f908', '0x10296f908') #Nested lists have same address

>>> i[3].append(6)

>>> j

>>> [1,2,3,[4,5,6]] #Updation of original nested list updated the copy as well

使用deepcopy：的平面列表示例>>> import copy

>>> i = [1,2,3]

>>> j = copy.deepcopy(i)

>>> hex(id(i)), hex(id(j))

>>> ('0x102b9b7c8', '0x102971cc8') #Both addresses are different

>>> i.append(4)

>>> j

>>> [1,2,3] #Updation of original list didn't affected copied variable

使用deepcopy：的嵌套列表示例>>> import copy

>>> i = [1,2,3,[4,5]]

>>> j = copy.deepcopy(i)

>>> hex(id(i)), hex(id(j))

>>> ('0x102b9b7c8', '0x102971cc8') #Both addresses are still different

>>> hex(id(i[3])), hex(id(j[3]))

>>> ('0x10296f908', '0x102b9b7c8') #Nested lists have different addresses

>>> i[3].append(6)

>>> j

>>> [1,2,3,[4,5]] #Updation of original nested list didn't affected the copied variable