Create common helpers and refactor charts

scripts/custom_chart.py

@@ -17,21 +17,7 @@ from typing import Iterable
 import matplotlib.dates as mdates
 import matplotlib.pyplot as plt
 import pandas as pd
-import sqlite3
-
-
-def save_figure(fig: plt.Figure, output: str | None, script_path: str) -> Path:
-    """Save ``fig`` to ``output`` or a timestamped path under ``outputs/``."""
-    out_path = (
-        Path(output)
-        if output is not None
-        else Path("outputs")
-        / f"{Path(script_path).stem}_{datetime.now().strftime('%Y%m%d_%H%M%S')}.png"
-    )
-    out_path.parent.mkdir(parents=True, exist_ok=True)
-    fig.savefig(out_path)
-    print(f"Saved figure to {out_path}")
-    return out_path
+from scripts.common import fetch_series_db, save_figure
 
 
 def fetch_series_multi(
@@ -41,29 +27,7 @@ def fetch_series_multi(
     db_path: str | Path = Path("data/fred.db"),
 ) -> pd.DataFrame:
     """Load one or more FRED series from a local SQLite DB."""
-    db_path = Path(db_path)
-    if not db_path.exists():
-        raise FileNotFoundError(
-            f"{db_path} not found. Run scripts/refresh_data.py on a machine with internet, commit the DB, then retry."
-        )
-
-    frames: list[pd.DataFrame] = []
-    with sqlite3.connect(db_path) as conn:
-        for name in series:
-            df = pd.read_sql(
-                f"SELECT date, {name} FROM {name}",
-                conn,
-                parse_dates=["date"],
-                index_col="date",
-            ).loc[start:end]
-            df.rename(columns={name: name}, inplace=True)
-            frames.append(df)
-
-    if not frames:
-        raise ValueError("No series loaded")
-
-    combined = pd.concat(frames, axis=1).sort_index()
-    return combined
+    return fetch_series_db(series, start, end, db_path)
 
 
 def plot_series(df: pd.DataFrame) -> plt.Figure: