python拷贝对象(deepcopy .vs. copy)

1. copy 浅拷贝，只拷贝父对象，不会拷贝对象内部的子对象，而是对子对象引用。

import copy
a = [1, [2, 3]]
b = copy.copy(a)
a[0] = 2
a[1][0] = 1

print 'a= ', a
print 'b= ', b

输出：

a= [2, [1, 3]]

b= [1, [1, 3]]

它等价于：

import copy
a = [1, [2, 3]]
b = a[:] #对于子对象只引用了
a[0] = 2
a[1][0] = 1

print 'a= ', a
print 'b= ', b

 

2. deepcopy  深拷贝 拷贝对象及其子对象

import copy
a = [1, [2, 3]]
b = copy.deepcopy(a)
a[0] = 2
a[1][0] = 1

print 'a= ', a
print 'b= ', b

输出：

a= [2, [1, 3]]

b= [2, [1, 3]]