MyMidas/backend/app/ml/net_worth_projection.py
megaproxy 61a7884ee5 Initial commit: MyMidas personal finance tracker
Full-stack self-hosted finance app with FastAPI backend and React frontend.

Features:
- Accounts, transactions, budgets, investments with GBP base currency
- CSV import with auto-detection for 10 UK bank formats
- ML predictions: spending forecast, net worth projection, Monte Carlo
- 7 selectable themes (Obsidian, Arctic, Midnight, Vault, Terminal, Synthwave, Ledger)
- Receipt/document attachments on transactions (JPEG, PNG, WebP, PDF)
- AES-256-GCM field encryption, RS256 JWT, TOTP 2FA, RLS, audit log
- Encrypted nightly backups + key rotation script
- Mobile-responsive layout with bottom nav

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-04-21 11:56:10 +00:00

102 lines
3.3 KiB
Python

from __future__ import annotations
import warnings
from datetime import date
from dateutil.relativedelta import relativedelta
import numpy as np
import pandas as pd
warnings.filterwarnings("ignore")
def _project_months(from_date: date, n: int) -> list[str]:
months = []
d = from_date.replace(day=1)
for i in range(1, n + 1):
months.append((d + relativedelta(months=i)).strftime("%Y-%m"))
return months
def project_net_worth(df: pd.DataFrame, years: int = 5) -> dict:
"""
df columns: ds (monthly datetime), y (net_worth float)
Returns history + 3-scenario projections.
"""
n_months = years * 12
today = date.today()
future_dates = _project_months(today, n_months)
history = [
{"date": row["ds"].strftime("%Y-%m"), "value": round(float(row["y"]), 2)}
for _, row in df.iterrows()
]
if df.empty or len(df) < 2:
# No data — return flat projection from 0
last_val = float(df["y"].iloc[-1]) if not df.empty else 0.0
flat = [{"date": d, "value": round(last_val, 2)} for d in future_dates]
return {
"history": history,
"projections": {"conservative": flat, "base": flat, "optimistic": flat},
"insufficient_data": True,
}
try:
from statsmodels.tsa.holtwinters import ExponentialSmoothing
values = df["y"].tolist()
if len(values) >= 12:
model = ExponentialSmoothing(values, trend="add", seasonal="add", seasonal_periods=12)
elif len(values) >= 4:
model = ExponentialSmoothing(values, trend="add", seasonal=None)
else:
model = ExponentialSmoothing(values, trend="add", seasonal=None)
fit = model.fit(optimized=True, disp=False)
base_fcast = fit.forecast(n_months)
# Estimate monthly trend from the fit
monthly_trend = float(np.mean(np.diff(base_fcast[:12]))) if len(base_fcast) >= 12 else 0.0
last_val = float(values[-1])
# Scale trends for scenarios
def build_scenario(scale: float) -> list[dict]:
pts = []
v = last_val
for i, d in enumerate(future_dates):
v = float(base_fcast[i]) + (scale - 1.0) * monthly_trend * (i + 1)
pts.append({"date": d, "value": round(v, 2)})
return pts
return {
"history": history,
"projections": {
"conservative": build_scenario(0.5),
"base": [{"date": d, "value": round(float(v), 2)} for d, v in zip(future_dates, base_fcast)],
"optimistic": build_scenario(1.5),
},
"insufficient_data": False,
}
except Exception:
# Fallback: linear trend from last 2 values
trend = float(df["y"].iloc[-1]) - float(df["y"].iloc[-2])
last_val = float(df["y"].iloc[-1])
def linear_scenario(t_scale: float) -> list[dict]:
return [
{"date": d, "value": round(last_val + t_scale * trend * (i + 1), 2)}
for i, d in enumerate(future_dates)
]
return {
"history": history,
"projections": {
"conservative": linear_scenario(0.5),
"base": linear_scenario(1.0),
"optimistic": linear_scenario(1.5),
},
"insufficient_data": False,
}