Pandas Groupby take first row

import pandas as pd
import numpy as np
df = pd.DataFrame({'id': np.array([1,1,2,3,3,3]),
                   'no': np.array([1,2,3,0,1,2]),
                   'col1': np.random.randn(6),
                   'col2': np.random.randn(6)})
df = df.sort_values(['id', 'no'], ascending=[1, 0])
df.groupby('id').first()