DataFrame Fillna con 0
df['column'] = df['column'].fillna(0)
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df['column'] = df['column'].fillna(0)sub2['income'].fillna((sub2['income'].mean()), inplace=True)# for the whole dataframe
df = df.fillna(axis=1, method='backfill')
# only for some columns
df[['A', 'B', 'C']] = df[['A', 'B', 'C']].fillna(axis=1, method='backfill')