How can I map the headers to columns in pandas?

Question

I have a dataframe like :

A    B    C 
1    0    0
1    1    0
0    1    0
0    0    1

I want to have :

 A    B    C  lab         


        

Answer 1

In [101]: df['label'] = df.apply(lambda x: ''.join(df.columns[x.astype(bool)].tolist()), axis=1)

In [102]: df
Out[102]:
   A  B  C label
0  1  0  0     A
1  1  1  0    AB
2  0  1  0     B
3  0  0  1     C

PS i would definitely chose @Ted's solution as it's much nicer and much much much ... faster