더미변수 다시 원래대로 돌리기

 

In [1]: import pandas as pd

In [2]: s = pd.Series(['a', 'b', 'a', 'c'])

In [3]: s
Out[3]: 
0    a
1    b
2    a
3    c
dtype: object

In [4]: dummies = pd.get_dummies(s)

In [5]: dummies
Out[5]: 
   a  b  c
0  1  0  0
1  0  1  0
2  1  0  0
3  0  0  1

In [6]: s2 = dummies.idxmax(axis=1)

In [7]: s2
Out[7]: 
0    a
1    b
2    a
3    c
dtype: object

 

idxmax() 함수 쓰면 됨