Pandas füllen NA mit Wert aus einer anderen Spalte
df['Cat1'].fillna(df['Cat2'])
macarrony00
df['Cat1'].fillna(df['Cat2'])
df['column'] = df['column'].fillna(0)
# based on another column value
df['column_1'].fillna(df['column_2'], inplace=True)
# selecting your desired columns
df[['a', 'b']] = df[['a', 'b']].fillna(df['c'], inplace=True)