方式一:使用切片 [:]
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# 浅拷贝 [:] old_list = [ 1 , 2 , [ 3 , 4 ]] new_list = old_list[:] old_list.append( 5 ) old_list[ 2 ][ 0 ] + = 97 print ( "Old list:" , old_list, "old list id:" , id (old_list), " old list[0] id:" , id (old_list[ 2 ])) print ( "new list:" , new_list, "new list id:" , id (new_list), " new list[0] id:" , id (new_list[ 2 ])) # 输出结果 Old list : [ 1 , 2 , [ 100 , 4 ], 5 ] old list id : 4537660608 old list [ 0 ] id : 4537659840 new list : [ 1 , 2 , [ 100 , 4 ]] new list id : 4537711424 new list [ 0 ] id : 4537659840 |
方式二:使用工厂函数
工厂函数简介
- 工厂函数看上去像函数,但实际是一个类
- 调用时,生成该数据类型类型的一个实例
可变对象的工厂函数
- list()
- set()
- dict()
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old_list = [ 1 , 2 , [ 3 , 4 ]] new_list = list (old_list) old_list.append( 5 ) old_list[ 2 ][ 0 ] + = 97 print ( "Old list:" , old_list, "old list id:" , id (old_list), " old list[0] id:" , id (old_list[ 2 ])) print ( "new list:" , new_list, "new list id:" , id (new_list), " new list[0] id:" , id (new_list[ 2 ])) |
集合
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old_set = { 1 , 2 , 3 } new_set = set (old_set) old_set.add( 4 ) print ( "Old set:" , old_set, "old set id:" , id (old_set)) print ( "new set:" , new_set, "new set id:" , id (new_set)) # 输出结果 Old set : { 1 , 2 , 3 , 4 } old set id : 4484723648 new set : { 1 , 2 , 3 } new set id : 4484723872 |
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old_dict = { "name" : "小明" } new_dict = dict (old_dict) old_dict[ "second" ] = "Python" print ( "Old dict:" , old_dict, "old dict id:" , id (old_dict)) print ( "new dict:" , new_dict, "new dict id:" , id (new_dict)) # 输出结果 Old dict : { 'name' : '小明' , 'second' : 'Python' } old dict id : 4514161536 new dict : { 'name' : '小明' } new dict id : 4515690304 |
方式三:使用数据类型自带的 copy 方法
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old_list = [ 1 , 2 , [ 3 , 4 ]] new_list = old_list.copy() old_list.append( 5 ) old_list[ 2 ][ 0 ] + = 97 print ( "Old list:" , old_list, "old list id:" , id (old_list), " old list[0] id:" , id (old_list[ 2 ])) print ( "new list:" , new_list, "new list id:" , id (new_list), " new list[0] id:" , id (new_list[ 2 ])) # 输出结果 Old list : [ 1 , 2 , [ 100 , 4 ], 5 ] old list id : 4309832000 old list [ 0 ] id : 4310372992 new list : [ 1 , 2 , [ 100 , 4 ]] new list id : 4309735296 new list [ 0 ] id : 4310372992 |
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old_set = { 1 , 2 , 3 } new_set = old_set.copy() old_set.add( 4 ) print ( "Old set:" , old_set, "old set id:" , id (old_set)) print ( "new set:" , new_set, "new set id:" , id (new_set)) # 输出结果 Old set : { 1 , 2 , 3 , 4 } old set id : 4309931392 new set : { 1 , 2 , 3 } new set id : 4309930944 |
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old_dict = { "name" : "小明" } new_dict = old_dict.copy() old_dict[ "second" ] = "Python" print ( "Old dict:" , old_dict, "old dict id:" , id (old_dict)) print ( "new dict:" , new_dict, "new dict id:" , id (new_dict)) # 输出结果 Old dict : { 'name' : '小明' , 'second' : 'Python' } old dict id : 4308452288 new dict : { 'name' : '小明' } new dict id : 4308452224 |
源码
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def copy( self , * args, * * kwargs): # real signature unknown """ Return a shallow copy of the list. """ pass |
已经写的很清楚,这是浅拷贝
方式四:使用 copy 模块的 copy 方法
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from copy import copy old_list = [ 1 , 2 , [ 3 , 4 ]] new_list = copy(old_list) old_list.append( 5 ) old_list[ 2 ][ 0 ] + = 97 print ( "Old list:" , old_list, "old list id:" , id (old_list), " old list[0] id:" , id (old_list[ 2 ])) print ( "new list:" , new_list, "new list id:" , id (new_list), " new list[0] id:" , id (new_list[ 2 ])) # 输出结果 Old list : [ 1 , 2 , [ 100 , 4 ], 5 ] old list id : 4381013184 old list [ 0 ] id : 4381159936 new list : [ 1 , 2 , [ 100 , 4 ]] new list id : 4381012800 new list [ 0 ] id : 4381159936 |
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from copy import copy old_set = { 1 , 2 , 3 } new_set = copy(old_set) old_set.add( 4 ) print ( "Old set:" , old_set, "old set id:" , id (old_set)) print ( "new set:" , new_set, "new set id:" , id (new_set)) # 输出结果 Old set : { 1 , 2 , 3 , 4 } old set id : 4381115552 new set : { 1 , 2 , 3 } new set id : 4381115776 |
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from copy import copy old_dict = { "name" : "小明" } new_dict = copy(old_dict) old_dict[ "second" ] = "Python" print ( "Old dict:" , old_dict, "old dict id:" , id (old_dict)) print ( "new dict:" , new_dict, "new dict id:" , id (new_dict)) # 输出结果 Old dict : { 'name' : '小明' , 'second' : 'Python' } old dict id : 4381159680 new dict : { 'name' : '小明' } new dict id : 4379632576 |
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原文链接:https://blog.csdn.net/qdPython/article/details/121121358