Add argparse options to refresh_data

scripts/refresh_data.py

@@ -1,33 +1,51 @@
 #!/usr/bin/env python3
-"""
-refresh_data.py
----------------
-Download UNRATE and DCOILWTICO from FRED and store them in SQLite
-(data/fred.db).  Run on a connected machine; commit the DB afterwards.
+"""refresh_data.py
+-----------------
+Download one or more FRED series into ``data/fred.db``.
+
+Run this script on a machine with internet access and commit the updated
+database afterwards.
+
+Example:
+    python scripts/refresh_data.py --series UNRATE CPIAUCSL --start 1960-01-01
 """
 
+from __future__ import annotations
+
 from datetime import date
+import argparse
 import pathlib
 import sqlite3
 
-import pandas as pd
 from pandas_datareader.data import DataReader
+import pandas as pd
 
 HERE = pathlib.Path(__file__).resolve().parent
 DATA_PATH = HERE.parent / "data"
 DB_FILE = DATA_PATH / "fred.db"
 
-START = "1948-01-01"          # earliest UNRATE observation
-END = date.today().isoformat()
-SERIES = ("UNRATE", "DCOILWTICO")
+DEFAULT_START = "1948-01-01"  # earliest UNRATE observation
+DEFAULT_END = date.today().isoformat()
+DEFAULT_SERIES = ("UNRATE", "DCOILWTICO")
 
 
-def main() -> None:
+def main(argv: list[str] | None = None) -> None:
+    p = argparse.ArgumentParser(description="Download FRED series to SQLite")
+    p.add_argument(
+        "--series",
+        nargs="+",
+        default=list(DEFAULT_SERIES),
+        help="FRED series names",
+    )
+    p.add_argument("--start", type=str, default=DEFAULT_START, help="start date")
+    p.add_argument("--end", type=str, default=DEFAULT_END, help="end date")
+    args = p.parse_args(argv)
+
     DATA_PATH.mkdir(exist_ok=True)
     with sqlite3.connect(DB_FILE) as conn:
-        for s in SERIES:
+        for s in args.series:
             print(f"↯ downloading {s} …")
-            df = DataReader(s, "fred", START, END)
+            df = DataReader(s, "fred", args.start, args.end)
             df.to_sql(s, conn, if_exists="replace", index_label="date")
             print(f"✓ wrote {s}: {len(df):,} rows")
     print(f"\nDone.  SQLite DB at {DB_FILE} ({DB_FILE.stat().st_size/1024:.0f} KB)")