python深浅copy详细代码解释

#date 2019/4/2

"""
浅拷贝---只拷贝最外层
深拷贝：导入 内置copy包
"""

import copy
l1 = [[1,2,3],[4,5,6]]
l2 = copy.deepcopy(l1)
print(l1)
print(l2)
l1[0][1] = 8
print(l1)     #深复制之后两者毫无关联了
print(l2)   

[[1, 2, 3], [4, 5, 6]]
[[1, 2, 3], [4, 5, 6]]
[[1, 8, 3], [4, 5, 6]]
[[1, 2, 3], [4, 5, 6]]

l3 = [[1,2,3],4,5,6]
l4 = l3
print(l3,l4)
l3[0][0] = 9   #简单赋值之后 两个数据更改同步进行
print(l3,l4)

[[1, 2, 3], 4, 5, 6] [[1, 2, 3], 4, 5, 6]
[[9, 2, 3], 4, 5, 6] [[9, 2, 3], 4, 5, 6]

l5 = [[1,2,3],[4,5,6]]
l6 = l5[:]
print(l5,l6)
l5[0][2] = 9
print(l5,l6)

l7 = [1,2,3]
l8 = l7[:]  #索引赋值的方式无法拷贝嵌套中的内容
print(l7,l8)
l7[0] = 9
print(l7,l8)

[[1, 2, 3], [4, 5, 6]] [[1, 2, 3], [4, 5, 6]]
[[1, 2, 9], [4, 5, 6]] [[1, 2, 9], [4, 5, 6]]
[1, 2, 3] [1, 2, 3]
[9, 2, 3] [1, 2, 3]