Answers for "replace all nan values with the apopraite value in dataframe"

replace nan in pandas

df['DataFrame Column'] = df['DataFrame Column'].fillna(0)

pandas replace null values with values from another column

#Python
#Col 1 = where you want the values replaced
#Col 2 = where you want to take the values from
df["Col 1"].fillna(df["Col 2"], inplace=True)