pd.fillna specific column code example
Example 1: pandas replace nan
data["Gender"].fillna("No Gender", inplace = True)
Example 2: DataFrame.fillna
>>> df.fillna(0)
A B C D
0 0.0 2.0 0.0 0
1 3.0 4.0 0.0 1
2 0.0 0.0 0.0 5
3 0.0 3.0 0.0 4