[英]How to add a column to a multi-indexed DataFrame?
我有一個像這樣的DataFrame:
upper level1 level2
lower name name
1 Mary Tom
2 ... ...
如果我想在level1
下添加另一列,我該怎么辦? 例如
upper level1 level2
lower name age name
1 Mary 13 Tom
2 ... ... ...
我可以使用df['level1'].loc[:,'name']
訪問數據,但我不知道如何添加/刪除列。
如果我只使用df.level1['age']=1
,Python會返回一個復制警告,並且DataFrame中沒有任何更改:
SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
if __name__ == '__main__':
嘗試這個:
df.insert(1, ('level1', 'age'), pd.Series([13]))
您可以在作業中使用元組:
In [11]: df[('level1', 'age')] = 13 # or a Series here, rather than a number
In [12]: df
Out[12]:
upper level1 level2 level1
lower name name age
0 1 Mary Tom 13
1 2 ... ... 13
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