[Python] 字典 dict { } 的 key, value 鍵、值 互換

.[Python] 字典 dict { } 的 key, item 鍵、值 互換

 

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(1) 字典鍵值互換, 方法一 for 循環:

mydict = {'a': 1, 'b': 2, 'c': 3}

mydict_new = {}

for key, value in mydict.items():

    mydict_new[value] = key

print(mydict)

print(mydict_new)

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>>> mydict = {'a': 1, 'b': 2, 'c': 3}

>>> mydict_new = {}

>>> for key, value in mydict.items():

...      mydict_new[value] = key

...

>>> print(mydict)

{'a': 1, 'b': 2, 'c': 3}

>>> print(mydict_new)

{1: 'a', 2: 'b', 3: 'c'}

>>>

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(2) 字典鍵值互換, 方法二 列表生成器 generator:

mydict = {'a': 1, 'b': 2, 'c': 3}

mydict_new = dict([value, key] for key, value in mydict.items())

print(mydict)

print(mydict_new)

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>>> mydict = {'a': 1, 'b': 2, 'c': 3}

>>> mydict_new = dict([value, key] for key, value in mydict.items())

>>> print(mydict)

{'a': 1, 'b': 2, 'c': 3}

>>> print(mydict_new)

{1: 'a', 2: 'b', 3: 'c'}

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(3) 字典鍵值互換, 方法三 zip:

mydict = {'a': 1, 'b': 2, 'c': 3}

mydict_new = dict(zip(mydict.values(), mydict.keys()))

print(mydict)

print(mydict_new)

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>>> mydict = {'a': 1, 'b': 2, 'c': 3}

>>> mydict_new = dict(zip(mydict.values(), mydict.keys()))

>>> print(mydict)

{'a': 1, 'b': 2, 'c': 3}

>>> print(mydict_new)

{1: 'a', 2: 'b', 3: 'c'}