how to replace 0 with nan values code example

Example 1: how to replace nan with 0 in pandas

df['product']=df['product'].fillna(0)
df['context']=df['context'].fillna(0)
df

Example 2: pandas replace nan with value above

>>> df = pd.DataFrame([[1, 2, 3], [4, None, None], [None, None, 9]])
>>> df.fillna(method='ffill')
   0  1  2
0  1  2  3
1  4  2  3
2  4  2  9