python 深浅拷贝

深浅拷贝

#对于 数字 和 字符串 而言，赋值、浅拷贝和深拷贝无意义，因为其永远指向同一个内存地址
	import copy
	a1 = 22255
	a2 = 22255
	print(id(a1),id(a2)) #3428240 3428240

#对于字典、元祖、列表 而言，进行赋值、浅拷贝和深拷贝时，其内存地址的变化是不同的。

	import copy
	#字典
	n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}
	##赋值
	n2 = n1
	print(n1,n2) #{'k1': 'wu', 'k2': 123, 'k3': ['alex', 456]} {'k1': 'wu', 'k2': 123, 'k3': ['alex', 456]}
	print(id(n1),id(n2))  #6674440 6674440 #内存地址一样
	##浅拷贝
	n3 = copy.copy(n1)
	print(n1,n3) #{'k1': 'wu', 'k2': 123, 'k3': ['alex', 456]} {'k1': 'wu', 'k2': 123, 'k3': ['alex', 456]}
	print(id(n1),id(n3)) #6936584 12067848  #浅拷贝第一级，内存地址相同
	print(id(n1['k3']),id(n3['k3'])) #18741768 18741768
	##深拷贝
	n4 = copy.deepcopy(n1)
	print(n1,n4) #{'k3': ['alex', 456], 'k2': 123, 'k1': 'wu'} {'k3': ['alex', 456], 'k1': 'wu', 'k2': 123}
	print(id(n1),id(n4)) #6805512 11736904
	print(id(n1['k3']),id(n4['k3'])) #7601032 7599496 #深拷贝第二级，内存地址也不相同
	
	#列表
	n1 = [1,2,3,4,5,[6,7],]
	##赋值
	n2 = n1
	print(n1,n2) #[1, 2, 3, 4, 5, [6, 7]] [1, 2, 3, 4, 5, [6, 7]]
	print(id(n1),id(n2)) #18609928 18609928
	print(id(n1[5]),id(n2[5])) #18609544 18609544
	##浅拷贝
	n3 = copy.copy(n1)
	print(n1,n3) #[1, 2, 3, 4, 5, [6, 7]] [1, 2, 3, 4, 5, [6, 7]]
	print(id(n1),id(n3)) #18609928 18232904
	print(id(n1[5]),id(n3[5])) #18609544 18609544
	##深拷贝
	n4 = copy.deepcopy(n1)
	print(n1,n4) #[1, 2, 3, 4, 5, [6, 7]] [1, 2, 3, 4, 5, [6, 7]]
	print(id(n1),id(n4)) #18609928 18611848
	print(id(n1[5]),id(n4[5])) #18609544 18611912


	#元组
	一个小插曲：
		import copy
		n1 = (1,2,3,4,5,(6,7,),)
		#赋值
		n2 = n1
		print('n1:',n1,'n2:',n2) #n1: (1, 2, 3, 4, 5, (6, 7)) n2: (1, 2, 3, 4, 5, (6, 7))
		print(id(n1),id(n2)) #10416584 10416584
		print(id(n1[5]),id(n2[5])) #18415304 18415304
		print(type(n1),type(2)) #<class 'tuple'> <class 'int'>
		#浅拷贝
		n3 = copy.copy(n1)
		print('n1:',n1,'n3:',n3) #n1: (1, 2, 3, 4, 5, (6, 7)) n2: (1, 2, 3, 4, 5, (6, 7))
		print(id(n1),id(n3)) #10416584 10416584
		print(id(n1[5]),id(n3[5])) #18415304 18415304
		print(type(n1),type(3)) #<class 'tuple'> <class 'int'>
		#深拷贝
		n4 = copy.deepcopy(n1)
		print('n1:',n1,'n4:',n4) #n1: (1, 2, 3, 4, 5, (6, 7)) n2: (1, 2, 3, 4, 5, (6, 7))
		print(id(n1),id(n4)) #10416584 10416584
		print(id(n1[5]),id(n4[5])) #18415304 18415304
		print(type(n1),type(5)) #<class 'tuple'> <class 'int'>

	再一个小插曲：
		import copy
		n1 = (1,2,3,4,5,[6,7,],)
		#赋值
		n2 = n1
		print('n1:',n1,'n2:',n2) #(1, 2, 3, 4, 5, [6, 7]) n2: (1, 2, 3, 4, 5, [6, 7])
		print(id(n1),id(n2)) #11465160 11465160
		print(id(n1[5]),id(n2[5])) #18480456 18480456
		print(type(n1),type(2)) #<class 'tuple'> <class 'int'>
		#浅拷贝
		n3 = copy.copy(n1)
		print('n1:',n1,'n3:',n3) #n1: (1, 2, 3, 4, 5, [6, 7]) n3: (1, 2, 3, 4, 5, [6, 7])
		print(id(n1),id(n3)) #11465160 11465160
		print(id(n1[5]),id(n3[5])) #18480456 18480456
		print(type(n1),type(3)) #<class 'tuple'> <class 'int'>
		#深拷贝
		n4 = copy.deepcopy(n1)
		print('n1:',n1,'n4:',n4) #n1: (1, 2, 3, 4, 5, [6, 7]) n4: (1, 2, 3, 4, 5, [6, 7])
		print(id(n1),id(n4)) #11465160 18109736
		print(id(n1[5]),id(n4[5])) #18480456 18478920
		print(type(n1),type(5)) #<class 'tuple'> <class 'int'>

出现以上问题有可能跟下面的说法有关：

案例代码

	import copy
	dic = {
	    "cpu":[80,],
	    "mem":[80,],
	    "disk":[80,],
	}
	
	print("old:",dic)
	new_dic1 = copy.copy(dic)
	new_dic1["cpu"][0] = 50
	print("old:",dic)
	print("浅拷贝:",new_dic1)
	#返回结果：
	#old: {'disk': [80], 'cpu': [80], 'mem': [80]}
	#浅拷贝: {'disk': [80], 'cpu': [50], 'mem': [80]}
	
	new_dic2 = copy.deepcopy(dic)
	new_dic2["cpu"][0] = 60
	print("old:",dic)
	print("深拷贝:",new_dic2)
	#返回结果
	# old: {'mem': [80], 'cpu': [50], 'disk': [80]}
	# 深拷贝: {'mem': [80], 'cpu': [60], 'disk': [80]}