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  • 浅谈python的深浅拷贝


    # 浅谈深浅拷贝

    >>> dic = {"one":["one1","one2"],"two":{"two1":"hello","two2":"world"}}
    >>>
    >>> dic
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}

    # 浅拷贝
    >>> dic2 = dic.copy() # 对dic进行浅拷贝
    >>> dic2
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>>
    >>> dic["one"][0] = "change2" # 修改dic的第二层数据
    >>> dic
    {'one': ['change2', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>> dic2
    {'one': ['change2', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    # 可见,当修改dic的第二层数据时,dic2也随之改变
    >>>
    >>> dic["one"] = "change1" # 修改dic的第一层数据
    >>> dic
    {'one': 'change1', 'two': {'two1': 'hello', 'two2': 'world'}}
    >>> dic2
    {'one': ['change2', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>>
    # 浅拷贝总结:当进行浅拷贝时,修改dic的第二层数据时,会影响到dic2;而修改dic的第一层数据时,dic2不会随着dic的改变而改变;(修改dic2与修改dic同理,这里进列举修改dic的例子)

    # 深拷贝
    >>>
    >>> import copy
    >>> dic
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>> dic2 = copy.deepcopy(dic) # 对dic进行深拷贝
    >>> dic2
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>>
    >>> dic["one"][0] = "chage2" # 修改dic的第二层数据
    >>> dic
    {'one': ['chage2', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>> dic2
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>>
    # 可见,当修改dic的第二层数据时,dic2并没有随着dic的改变而改变
    >>>
    >>> dic["one"] = "CHAGE1"
    >>> dic
    {'one': 'CHAGE1', 'two': {'two1': 'hello', 'two2': 'world'}}
    >>> dic2
    {'one': ['one1', 'one2'], 'two': {'two1': 'hello', 'two2': 'world'}}
    >>>
    # 修改dic的第一层数据时,dic2也没有随之改变

    # 深拷贝总结:当进行深拷贝时,两者都是相互独立的,不管修改哪一个,都不会影响到对方。


    ## 深浅拷贝总结:浅拷贝只是第一层是独立的,其他层公用;而深拷贝是每一层都是独立的,修改都不会影响到对方。

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  • 原文地址:https://www.cnblogs.com/relax1949/p/9316337.html
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