def model_poly_jauge_price(day,od):
       
   df = pd.read_csv('/home/groupevsc.com/abdesselem_hantour/Téléchargements/ods_jauge_price_F.csv')
   df_day = df[df['day_name']==day]
   df_day_od = df_day[df_day['od']==od]
   df_final = df_day_od[['BOOKING_WINDOW','MT_VNT_EUR_VOY']]
   obs_day = df_final['MT_VNT_EUR_VOY'].reset_index()
   del obs_day ['index']

   x = list(df_final['BOOKING_WINDOW'])
   y = list(df_final['MT_VNT_EUR_VOY'])

   fitted = np.polyfit(x,y,3)
   func_third_order =np.poly1d(fitted)
   pas = range(1,90,1)
   return  plt.plot(func_third_order(pas),'g'),\
           plt.plot(obs_day,'r'),\
           plt.suptitle('Median prix pour Vendredi OD:' + od),\
           plt.xlabel('Booking Window'),\
           plt.ylabel('Median'),\
           plt.legend(["third_order","Observed"])