[英]pandas – apply function to DataFrame row-wise, resulting in a new DataFrame of different dimensions
我希望能够将一个函数应用于DataFrame
(逐行),以便它可以返回不一定具有与原始维度或索引相同的新DataFrame
。
假设我有一个DataFrame
, df
:
A B C D
0 A0 B0 C0 D0
1 A1 B1 C1 D1
2 A2 B2 C2 D2
3 A3 B3 C3 D3
和一个函数foo()
:
>>> def foo(series):
... series['E'] = 'NEW_STUFF'
... series['F'] = 'MORE_NEW_STUFF'
... df = pd.DataFrame(series.drop('B')).transpose()
... return pd.concat([df,df], keys='qw')
...
这样
>>> foo(df.iloc[0])
A C D E F
q 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
w 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
我想将foo()
应用于df
,从而导致新的DataFrame
,其中在每一行上运行foo()
的结果都被堆叠到单个DataFrame
,就像
A C D E F
q 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
w 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
q 1 A1 C1 D1 NEW_STUFF MORE_NEW_STUFF
w 1 A1 C1 D1 NEW_STUFF MORE_NEW_STUFF
q 2 A2 C2 D2 NEW_STUFF MORE_NEW_STUFF
w 2 A2 C2 D2 NEW_STUFF MORE_NEW_STUFF
q 3 A3 C3 D3 NEW_STUFF MORE_NEW_STUFF
w 3 A3 C3 D3 NEW_STUFF MORE_NEW_STUFF
但是,运行df.apply(foo, axis=1)
不会返回此值。 相反,我得到
>>> df.apply(foo, axis=1)
0 A C D E F
q 0...
1 A C D E F
q 1...
2 A C D E F
q 2...
3 A C D E F
q 3...
dtype: object
我需要在上面进行哪些修改才能获得所需的结果?
试试看
pd.concat([foo(y) for _,y in df.iterrows()])
Out[64]:
A C D E F
q 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
w 0 A0 C0 D0 NEW_STUFF MORE_NEW_STUFF
q 1 A1 C1 D1 NEW_STUFF MORE_NEW_STUFF
w 1 A1 C1 D1 NEW_STUFF MORE_NEW_STUFF
q 2 A2 C2 D2 NEW_STUFF MORE_NEW_STUFF
w 2 A2 C2 D2 NEW_STUFF MORE_NEW_STUFF
q 3 A3 C3 D3 NEW_STUFF MORE_NEW_STUFF
w 3 A3 C3 D3 NEW_STUFF MORE_NEW_STUFF
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