add statistics for irregular expenses, interpret negative transactions as outgoing and positive as incoming

financeplanner/calc.py

@@ -6,6 +6,10 @@ from django.db.models import Q
 
 from financeplanner.utils import current_date
 
+days_per_year = Decimal("365.25")
+days_per_month = days_per_year / Decimal("12")
+days_per_week = Decimal("7")
+
 
 def _floor_to_first_two_places(dec):
     if dec < 100:
@@ -21,6 +25,9 @@ class ActualTransaction:
         self.subject = subject
         self.amount = amount
 
+    def __str__(self):
+        return f"ActualTransaction({self.date}, {self.subject}, {self.amount})"
+
 
 class DailyStat:
     def __init__(self, date, balance_amount, actual_transactions, resulting_amount):
@@ -32,6 +39,10 @@ class DailyStat:
         self.color_class = ""
         self.opacity_class = ""
 
+    def __str__(self):
+        return f"DailyStat({self.date}, {self.balance_amount}, " \
+               f"{len(self.actual_transactions)} a. transactions, {self.resulting_amount})"
+
     def generate_graph_bar_attributes(self, amount_scale, today):
         if self.resulting_amount is not None:
             self.percentage = int((self.resulting_amount / amount_scale) * 100)
@@ -68,6 +79,9 @@ class Statistics:
         self.avg_monthly_income = 0
         self.avg_monthly_expenses = 0
         self.avg_monthly_result = 0
+        self.avg_daily_irregular_expenses = 0
+        self.avg_weekly_irregular_expenses = 0
+        self.avg_monthly_irregular_expenses = 0
 
         self._fetch_relevant_balances()
         self._fetch_relevant_transactions()
@@ -150,7 +164,7 @@ class Statistics:
                 if transaction.date == iter_date:
                     actual_transactions.append(transaction)
                     if iter_amount is not None:
-                        iter_amount -= transaction.amount
+                        iter_amount += transaction.amount
 
             if iter_amount is not None:
                 self.daily_stats.append(DailyStat(
@@ -174,20 +188,38 @@ class Statistics:
 
     def _calculate_analysis(self):
         booked = Q(booking_date__lte=self.today)
-        incoming = Q(amount__lt=0)
+        incoming = Q(amount__gt=0)
-        outgoing = Q(amount__gt=0)
+        outgoing = Q(amount__lt=0)
         recurring = Q(recurring_months__isnull=False) & (
                 Q(not_recurring_after__isnull=True) | Q(not_recurring_after__gte=self.today))
 
         in_trans = self.user.transactions.filter(booked & incoming & recurring)
         in_trans_per_month = [t.amount / t.recurring_months for t in in_trans]
-        self.avg_monthly_income = -sum(in_trans_per_month)
+        self.avg_monthly_income = sum(in_trans_per_month)
 
         out_trans = self.user.transactions.filter(booked & outgoing & recurring)
         out_trans_per_month = [t.amount / t.recurring_months for t in out_trans]
         self.avg_monthly_expenses = sum(out_trans_per_month)
 
-        self.avg_monthly_result = self.avg_monthly_income - self.avg_monthly_expenses
+        self.avg_monthly_result = self.avg_monthly_income + self.avg_monthly_expenses
+
+        daily_irregular_expenses = []
+        if len(self.balances) > 1:
+            for i in range(1, len(self.balances)):
+                previous_balance = self.balances[i - 1]
+                current_balance = self.balances[i]
+                day_before = current_balance.date - relativedelta(days=1)
+                relevant_stats = [s for s in self.daily_stats if s.date == day_before]
+                if relevant_stats and day_before > previous_balance.date:
+                    assert len(relevant_stats) == 1, \
+                        f"daily stats should be unique per date, but here are {relevant_stats}"
+                    amount_diff = current_balance.amount - relevant_stats[0].resulting_amount
+                    time_diff = current_balance.date - previous_balance.date
+                    daily_irregular_expenses.append(amount_diff / time_diff.days)
+        if daily_irregular_expenses:
+            self.avg_daily_irregular_expenses = sum(daily_irregular_expenses) / len(daily_irregular_expenses)
+            self.avg_weekly_irregular_expenses = self.avg_daily_irregular_expenses * days_per_week
+            self.avg_monthly_irregular_expenses = self.avg_daily_irregular_expenses * days_per_month
 
     def get_daily_stats_in_range(self):
         return [s for s in self.daily_stats if self.start <= s.date <= self.end]

financeplanner/templates/financeplanner/index.html

@@ -44,36 +44,38 @@
 
 <div class="main-container">
     <h2>Analysis</h2>
+    <p>current average amounts per month:</p>
     <table>
         <tbody>
         <tr>
-            <td>current average monthly income</td>
+            <td>income</td>
             <td>{{ avg_monthly_income|euro }}</td>
         </tr>
         <tr>
-            <td>current average monthly expenses</td>
+            <td>expenses</td>
             <td>{{ avg_monthly_expenses|euro }}</td>
         </tr>
         <tr>
-            <td>current average monthly result</td>
+            <td>result</td>
             <td>{{ avg_monthly_result|euro }}</td>
         </tr>
         </tbody>
     </table>
 
+    <p>average irregular expenses based on the last half-a-year:</p>
     <table>
         <tbody>
         <tr>
-            <td>irregular expenses / month</td>
+            <td>monthly</td>
-            <td>0</td>
+            <td>{{ avg_monthly_irregular_expenses|euro }}</td>
         </tr>
         <tr>
-            <td>irregular expenses / week</td>
+            <td>weekly</td>
-            <td>0</td>
+            <td>{{ avg_weekly_irregular_expenses|euro }}</td>
         </tr>
         <tr>
-            <td>irregular expenses / day</td>
+            <td>daily</td>
-            <td>0</td>
+            <td>{{ avg_daily_irregular_expenses|euro }}</td>
         </tr>
         </tbody>
     </table>

financeplanner/views.py

@@ -18,5 +18,8 @@ def index(request):
         "avg_monthly_income": statistics.avg_monthly_income,
         "avg_monthly_expenses": statistics.avg_monthly_expenses,
         "avg_monthly_result": statistics.avg_monthly_result,
+        "avg_daily_irregular_expenses": statistics.avg_daily_irregular_expenses,
+        "avg_weekly_irregular_expenses": statistics.avg_weekly_irregular_expenses,
+        "avg_monthly_irregular_expenses": statistics.avg_monthly_irregular_expenses,
     }
     return render(request, "financeplanner/index.html", context)