Add concurrent geocoding with ThreadPoolExecutor

- Use --workers to set concurrent thread count (default 3)
- Speed up coordinate lookup by ~3x with 3 workers
- Maintain Nominatim rate limiting per thread

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cpc_direct_stations.py

@@ -17,6 +17,7 @@
 from __future__ import annotations
 
 import argparse
+import concurrent.futures
 import csv
 import json
 import os
@@ -198,10 +199,15 @@ def geocode(address: str, station_name: str, city: str, district: str) -> Option
     return None
 
 
-def add_coordinates(stations: List[Dict[str, str]], delay: float = 1.0) -> List[Dict[str, str]]:
-    """為站點資料加上座標資訊（使用快取）。"""
+def add_coordinates(stations: List[Dict[str, str]], delay: float = 1.0, workers: int = 3) -> List[Dict[str, str]]:
+    """為站點資料加上座標資訊（使用快取+並發查詢）。
+
+    Args:
+        stations: 站點列表
+        delay: 每個查詢間隔秒數（Nominatim 限制約 1 秒）
+        workers: 並發查詢執行緒數（預設 3，Nominatim 免費版限制）
+    """
     cache = load_coords_cache()
-    cache_updated = False
     missing_coords = []
 
     # 先從快取讀取
@@ -215,10 +221,11 @@ def add_coordinates(stations: List[Dict[str, str]], delay: float = 1.0) -> List[
             station["經度"] = ""
             missing_coords.append(station)
 
-    # 查詢缺少的座標
+    # 並發查詢缺少的座標
     if missing_coords:
         print(f"快取命中: {len(stations) - len(missing_coords)}/{len(stations)}，需查詢: {len(missing_coords)}", file=sys.stderr)
-        for station in missing_coords:
+
+        def query_one(station: Dict[str, str]) -> tuple[Dict[str, str], Optional[Dict[str, float]]]:
             full_address = f"{station['縣市']}{station['鄉鎮區']}{station['地址']}"
             coords = geocode(
                 address=full_address,
@@ -226,16 +233,20 @@ def add_coordinates(stations: List[Dict[str, str]], delay: float = 1.0) -> List[
                 city=station["縣市"],
                 district=station["鄉鎮區"],
             )
-            if coords:
-                station["緯度"] = str(coords["lat"])
-                station["經度"] = str(coords["lon"])
-                key = make_cache_key(station)
-                cache[key] = coords
-                cache_updated = True
             time.sleep(delay)  # 避免 Nominatim 請求過快
+            return (station, coords)
 
-        if cache_updated:
-            save_coords_cache(cache)
+        with concurrent.futures.ThreadPoolExecutor(max_workers=workers) as executor:
+            futures = {executor.submit(query_one, s): s for s in missing_coords}
+            for future in concurrent.futures.as_completed(futures):
+                station, coords = future.result()
+                if coords:
+                    station["緯度"] = str(coords["lat"])
+                    station["經度"] = str(coords["lon"])
+                    key = make_cache_key(station)
+                    cache[key] = coords
+
+        save_coords_cache(cache)
 
     return stations
 
@@ -365,7 +376,8 @@ def main() -> None:
     parser.add_argument("--format", choices=["text", "json", "csv"], default="text")
     parser.add_argument("--out", help="輸出到檔案路徑")
     parser.add_argument("--coords", action="store_true", help="加上座標資訊（使用 Nominatim OSM API）")
-    parser.add_argument("--delay", type=float, default=1.0, help="座標查詢間隔秒數（預設 1.0，Nominatim 限制）")
+    parser.add_argument("--delay", type=float, default=1.0, help="座標查詢間隔秒數（預設 1.0）")
+    parser.add_argument("--workers", type=int, default=3, help="並發查詢執行緒數（預設 3）")
     args = parser.parse_args()
 
     html = build_query_html(city=args.city, keyword=args.keyword)
@@ -373,7 +385,7 @@ def main() -> None:
     stations = filter_stations(stations, args.keyword)
 
     if args.coords:
-        stations = add_coordinates(stations, delay=args.delay)
+        stations = add_coordinates(stations, delay=args.delay, workers=args.workers)
 
     if args.format == "json":
         output_json(stations, args.out)