1>>> df = pd.DataFrame([[1, 25], [4, 40], [7, 45]],
2 index=['cobra', 'viper', 'sidewinder'],
3 columns=['max_speed', 'shield'])
4>>> df
5 max_speed shield
6cobra 1 25
7viper 4 40
8sidewinder 7 45
9
10>>> df.loc[df['shield'] > 35] = 0
11>>> df
12 max_speed shield
13cobra 1 25
14viper 4 0
15sidewinder 7 0
16