python中的赋值、copy、deepcopy

import copy
'''
 直接赋值：其实就是对象的引用（别名）。
 copy 模块的 copy 方法，拷贝父对象，不会拷贝对象的内部的子对象。
 copy 模块的 deepcopy 方法，完全拷贝了父对象及其子对象。
''' 
origin = [1, 2, [3, 4]]
cop1 = copy.copy(origin)
cop2 = copy.deepcopy(origin)
cop3=origin
 
print(origin)
print(cop1)
print(cop2)
print(cop3)
 
origin[2][0] = "hey!"  #改变
print("##################")
 
print(origin)
print(cop1)
print(cop2)   # 深度拷贝不变
print(cop3)
 
[1, 2, [3, 4]]
[1, 2, [3, 4]]
[1, 2, [3, 4]]
[1, 2, [3, 4]]
##################
[1, 2, ['hey!', 4]]
[1, 2, ['hey!', 4]]
[1, 2, [3, 4]]
[1, 2, ['hey!', 4]]

 这个原理适用于list、dict数据类型。下面再放一个dict类型的例子。

import copy

print("使用copy")
dict1={"key1":"val1","k1":{"name":"lilei"}}
dict2=copy.copy(dict1)
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)

dict1["key1"] = "val1_new"
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)

dict1["k1"]["name"] = "lilei_new"
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)

print("\n")
print("---------------")
print("使用deepcopy")
dict1={"key1":"val1","k1":{"name":"lilei"}}
dict2=copy.deepcopy(dict1)
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)

dict1["key1"] = "val1_new"
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)

dict1["k1"]["name"] = "lilei_new"
print("dict1= %r" % dict1)
print("dict2= %r" % dict2)
'''
使用copy
dict1= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict1= {'key1': 'val1_new', 'k1': {'name': 'lilei'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict1= {'key1': 'val1_new', 'k1': {'name': 'lilei_new'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei_new'}}


---------------
使用deepcopy
dict1= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict1= {'key1': 'val1_new', 'k1': {'name': 'lilei'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei'}}
dict1= {'key1': 'val1_new', 'k1': {'name': 'lilei_new'}}
dict2= {'key1': 'val1', 'k1': {'name': 'lilei'}}
'''