Creating an empty MultiIndex

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没有蜡笔的小新
没有蜡笔的小新 2021-02-01 15:29

I would like to create an empty DataFrame with a MultiIndex before assigning rows to it. I already found that empty DataFrames

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  •  青春惊慌失措
    2021-02-01 15:54

    The solution is to leave out the labels. This works fine for me:

    >>> my_index = pd.MultiIndex(levels=[[],[],[]],
                                 labels=[[],[],[]],
                                 names=[u'one', u'two', u'three'])
    >>> my_index
    MultiIndex(levels=[[], [], []],
               labels=[[], [], []],
               names=[u'one', u'two', u'three'])
    >>> my_columns = [u'alpha', u'beta']
    >>> df = pd.DataFrame(index=my_index, columns=my_columns)
    >>> df
    Empty DataFrame
    Columns: [alpha, beta]
    Index: []
    >>> df.loc[('apple','banana','cherry'),:] = [0.1, 0.2]
    >>> df
                        alpha beta
    one   two    three            
    apple banana cherry   0.1  0.2
    

    Hope that helps!

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