fix: cashflow amount must be indexed in plot_forecast_monte_carlo

main.py

@@ -66,11 +66,11 @@
 # print(w)
 
 
-df = pf.dcf.wealth_with_assets
-df.plot()
+# df = pf.dcf.wealth_with_assets
+# df.plot()
 # print("portfolio balance \n", df.iloc[-1, :].describe())
 
-# pf.dcf.plot_forecast_monte_carlo(backtest=True)
+pf.dcf.plot_forecast_monte_carlo(backtest=True)
 
 
 

okama/common/helpers/helpers.py

@@ -586,7 +586,7 @@ def subtract_years(dt: pd.Timestamp, years: int) -> pd.Timestamp:
         )
 
     @staticmethod
-    def get_difference_in_months(last_day: pd.Timestamp, first_day: pd.Timestamp):
+    def get_difference_in_months(last_day: pd.Timestamp, first_day: pd.Timestamp) -> pd.DateOffset:
         return last_day.to_period("M") - first_day.to_period("M")
 
     @staticmethod

okama/portfolio.py

@@ -2760,6 +2760,11 @@ def plot_forecast_monte_carlo(
             last_backtest_value = s1.iloc[-1]
             if last_backtest_value > 0:
                 self.cashflow_parameters.initial_investment = last_backtest_value
+                if self.cashflow_parameters.name == "fixed_amount":
+                    months = helpers.Date.get_difference_in_months(self.parent.last_date, self.parent.first_date).n
+                    years = months / settings._MONTHS_PER_YEAR
+                    periods = years / settings.frequency_periods_per_year[self.cashflow_parameters.frequency]
+                    self.cashflow_parameters.amount *= (1.0 + self.cashflow_parameters.indexation) ** periods
                 s2 = self.monte_carlo_wealth
                 for s in s2:
                     s2[s].plot(legend=None)