Update app.py

app.py

@@ -76,11 +76,16 @@ with tab1:
 with tab2:
     st.header("SWP Calculator")
 
-    def calculate_swp(initial_investment, monthly_withdrawal, annual_rate, years):
+    # Add inflation_rate and withdrawal_increase_rate parameters
+    # Add inflation_rate and withdrawal_increase_rate parameters
+    def calculate_swp(initial_investment, monthly_withdrawal, annual_rate, years, inflation_rate, withdrawal_increase_rate):
         monthly_rate = annual_rate / 12 / 100
+        # Convert percentage rate to decimal for calculation
+        withdrawal_increase_rate_decimal = withdrawal_increase_rate / 100.0
         num_months = years * 12
         
         balance = float(initial_investment) # Use float for precision
+        current_monthly_withdrawal = float(monthly_withdrawal) # Start with the initial withdrawal amount
         total_interest_earned = 0.0
         total_withdrawn = 0.0
         
@@ -91,10 +96,13 @@ with tab2:
         monthly_withdrawals = [0.0] # Withdrawal made *during* month i is stored at index i
 
         for month in range(1, num_months + 1):
-            # Determine actual withdrawal amount first
-            # Using float(monthly_withdrawal) assumes withdrawal continues even if balance is insufficient
-            actual_withdrawal = float(monthly_withdrawal) 
-            # A more robust approach could be: actual_withdrawal = min(balance, float(monthly_withdrawal))
+            # Increase withdrawal amount at the start of each year (after the first year)
+            if month > 1 and (month - 1) % 12 == 0:
+                current_monthly_withdrawal *= (1 + withdrawal_increase_rate_decimal)
+
+            # Determine actual withdrawal amount first using the current (potentially increased) amount
+            actual_withdrawal = current_monthly_withdrawal 
+            # A more robust approach could be: actual_withdrawal = min(balance, current_monthly_withdrawal)
             # but we stick closer to the original implicit logic for now.
             
             # Subtract withdrawal from the balance
@@ -157,11 +165,15 @@ with tab2:
     monthly_withdrawal = st.number_input('Monthly Withdrawal', value=100000, step=1000, format='%d', key="swp_monthly")
     annual_rate = st.number_input('Annual Interest Rate (%)', value=8.0, step=0.1, format='%.1f', key="swp_rate")
     years = st.number_input('Investment Period (Years)', value=20, step=1, format='%d', key="swp_years")
+    # Add new input fields
+    inflation_rate = st.number_input('Expected Inflation Rate (%)', value=6.0, step=0.1, format='%.1f', key="swp_inflation")
+    withdrawal_increase_rate = st.number_input('Annual Withdrawal Increase (%)', value=0.0, step=0.1, format='%.1f', key="swp_increase")
+
 
     if st.button('Calculate SWP'):
-        # Unpack all four return values from the updated function
+        # Pass the new input values to the function
         final_balance_calc, total_interest_calc, total_withdrawal_calc, df = calculate_swp(
-            initial_investment, monthly_withdrawal, annual_rate, years
+            initial_investment, monthly_withdrawal, annual_rate, years, inflation_rate, withdrawal_increase_rate
         )
         
         st.subheader('SWP Projection')