pandas fillna with different values code example

Example 1: pandas fill na with value from another column

df['Cat1'].fillna(df['Cat2'])

Example 2: dataframe fillna with 0

df['column'] = df['column'].fillna(0)

Example 3: 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