null.py

# Replacing missing values in Glucose column with median of respective class.
def impute_Glucose(cols):
    Glucose=cols[0]
    Outcome=cols[1]
    if pd.isnull(Glucose):
        if Outcome == 0:
           return 120
        else:
            return 142
    else:
        return Glucose
df_copy['Glucose']=df_copy[['Glucose','Outcome']].apply(impute_Glucose, axis=1)