how to avoid ''SettingWithCopyWarning'' python code example

Example 1: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

import pandas as pd
pd.options.mode.chained_assignment = None  # default='warn'

Example 2: settingwithcopywarning pandas

>>> df = pd.DataFrame(data=data, index=index)

>>> df.loc[mask, "z"] = 0
>>> df
    x   y   z
a   1   1   0
b   2   3  98
c   4   9   0
d   8  27   0
e  16  81  64