賦值、淺拷貝以及深拷貝的區別
阿新 • • 發佈：2018-01-21
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字符串賦值
>>> >>> str1 = ‘standby‘ >>> >>> str2 = str1 >>> >>> print str1==str2, str1 is str2 True True >>> >>> id(str1) 139792206350496 >>> id(str2) 139792206350496 >>>
補充
>>> >>> a = ‘standby‘ >>> b = ‘standby‘ >>> >>> a == b True >>> a is b True >>> >>> id(a) 139792206350496 >>> id(b) 139792206350496 >>>
字符串淺拷貝方式一
>>> >>> import copy >>> str1 = ‘standby‘ >>> >>> str2 = copy.copy(str1) >>> >>> print str1==str2, str1 is str2 True True >>> >>> id(str1) 139792206350496 >>> id(str2) 139792206350496 >>>
字符串淺拷貝方式二
>>> >>> str1 = ‘standby‘ >>> >>> str2 = str1[:] >>> >>> print str1==str2, str1 is str2 True True >>> >>> id(str1) 139792206350496 >>> id(str2) 139792206350496 >>>
字符串深拷貝
>>> >>> import copy >>> str1 = ‘standby‘ >>> >>> str2 = copy.deepcopy(str1) >>> >>> print str1==str2, str1 is str2 True True >>> >>> id(str1) 139792206350496 >>> id(str2) 139792206350496 >>>
列表賦值
>>> >>> list1 = [1, 2, [1, 2]] >>> >>> list2 = list1 >>> >>> print list1==list2, list1 is list2 True True >>> >>> id(list1) 139792206344992 >>> id(list2) 139792206344992 >>>
補充
>>> >>> list1 = [1, 2, [‘a‘, ‘c‘]] >>> list2 = [1, 2, [‘a‘, ‘c‘]] >>> >>> list1 == list2 True >>> list1 is list2 False >>> >>> id(list1) 139792206356704 >>> id(list2) 139792206348088 >>>
列表淺拷貝方式一
>>> >>> import copy >>> list1 = [1, 2, [1, 2]] >>> >>> list2 = copy.copy(list1) >>> >>> print list1==list2, list1 is list2 True False >>> >>> >>> id(list1) 139792206344920 >>> id(list2) 139792206356560 >>>
列表淺拷貝方式二
>>> >>> list1 = [1, 2, [1, 2]] >>> >>> list2 = list1[:] >>> >>> print list1==list2, list1 is list2 True False >>> >>> id(list1) 139792206356704 >>> id(list2) 139792206344992 >>>
列表深拷貝
>>> >>> import copy >>> list1 = [1, 2, 3, 4] >>> >>> list2 = copy.deepcopy(list1) >>> >>> print list1==list2, list1 is list2 True False >>> >>> id(list1) 139792206344992 >>> id(list2) 139792206344920 >>>
淺拷貝情況下的修改
>>> >>> import copy >>> list1 = [1, 2, [‘a‘, ‘c‘]] >>> >>> list2 = copy.copy(list1) >>> print list1==list2, list1 is list2 True False >>> id(list1) 139792206358720 >>> id(list2) 139792206359080 >>> >>> list2[2].append(‘k‘) >>> print list2,list1 [1, 2, [‘a‘, ‘c‘, ‘k‘]] [1, 2, [‘a‘, ‘c‘, ‘k‘]] >>> id(list1) 139792206358720 >>> id(list2) 139792206359080 >>>
深拷貝情況下的修改
>>> >>> import copy >>> list1 = [1, 2, [‘a‘, ‘c‘]] >>> >>> list2 = copy.deepcopy(list1) >>> print list1==list2, list1 is list2 True False >>> id(list1) 139792206344920 >>> id(list2) 139792206358720 >>> >>> list2[2].append(‘k‘) >>> print list2,list1 [1, 2, [‘a‘, ‘c‘, ‘k‘]] [1, 2, [‘a‘, ‘c‘]] >>> id(list1) 139792206344920 >>> id(list2) 139792206358720 >>>
賦值、淺拷貝以及深拷貝的區別