Get column names for max values over a certain row in a pandas DataFrame

Question

In the DataFrame

import pandas as pd 
df=pd.DataFrame({\'col1\':[1,2,3],\'col2\':[3,2,1],\'col3\':[1,1,1]},index= [\'row1\',\'row2\',\'row3\'])
print df
             


        

Answer 1

you could also use apply and create a method such has:

def returncolname(row, colnames):
    return colnames[np.argmax(row.values)]

df['colmax'] = df.apply(lambda x: returncolname(x, df.columns), axis=1)

Out[62]: 
row1    col2
row2    col1
row3    col1
dtype: object

an you can use df.max(axis=1) to extract maxes

df.max(axis=1)
Out[69]: 
row1    3
row2    2
row3    3