Reversing 'one-hot' encoding in Pandas

I want to go from this data frame which is basically one hot encoded.

 In [2]: pd.DataFrame({"monkey":[0,1,0],"rabbit":[1,0,0],"fox":[0,0,1]})

    Out[2]:
       fox  monkey  rabbit
    0    0       0       1
    1    0       1       0
    2    1       0       0
    3    0       0       0
    4    0       0       0

To this one which is 'reverse' one-hot encoded.

    In [3]: pd.DataFrame({"animal":["monkey","rabbit","fox"]})
    Out[3]:
       animal
    0  monkey
    1  rabbit
    2     fox

I imagine there's some sort of clever use of apply or zip to do thins but I'm not sure how... Can anyone help?

I've not had much success using indexing etc to try to solve this problem.

UPDATE: i think ayhan is right and it should be:

df.idxmax(axis=1)

Demo:

In [40]: s = pd.Series(['dog', 'cat', 'dog', 'bird', 'fox', 'dog'])

In [41]: s
Out[41]:
0     dog
1     cat
2     dog
3    bird
4     fox
5     dog
dtype: object

In [42]: pd.get_dummies(s)
Out[42]:
   bird  cat  dog  fox
0   0.0  0.0  1.0  0.0
1   0.0  1.0  0.0  0.0
2   0.0  0.0  1.0  0.0
3   1.0  0.0  0.0  0.0
4   0.0  0.0  0.0  1.0
5   0.0  0.0  1.0  0.0

In [43]: pd.get_dummies(s).idxmax(1)
Out[43]:
0     dog
1     cat
2     dog
3    bird
4     fox
5     dog
dtype: object

OLD answer: (most probably, incorrect answer)

try this:

In [504]: df.idxmax().reset_index().rename(columns={'index':'animal', 0:'idx'})
Out[504]:
   animal  idx
0     fox    2
1  monkey    1
2  rabbit    0

data:

In [505]: df
Out[505]:
   fox  monkey  rabbit
0    0       0       1
1    0       1       0
2    1       0       0
3    0       0       0
4    0       0       0

I would use apply to decode the columns:

In [2]: animals = pd.DataFrame({"monkey":[0,1,0,0,0],"rabbit":[1,0,0,0,0],"fox":[0,0,1,0,0]})

In [3]: def get_animal(row):
   ...:     for c in animals.columns:
   ...:         if row[c]==1:
   ...:             return c

In [4]: animals.apply(get_animal, axis=1)
Out[4]: 
0    rabbit
1    monkey
2       fox
3      None
4      None
dtype: object