refactor select_nearest_stations to use a dictionary for station distances to avoid duplicates

app.py

@@ -418,12 +418,16 @@ def calculate_distance(lat1, lon1, lat2, lon2):
 
 def select_nearest_stations(st, epicenter_lat, epicenter_lon, n_stations=25):
     """從 site_info（1000+ 個輸入測站）中選擇距離震央最近的 n 個測站"""
-    station_distances = []
+    station_distances = {}  # 改用字典避免重複
 
     # 計算每個測站到震央的距離
     for tr in st:
         station_code = tr.stats.station
 
+        # 如果這個測站已經處理過，跳過（避免重複計算不同分量）
+        if station_code in station_distances:
+            continue
+
         # 從 site_info 中查詢測站位置
         try:
             station_data = site_info[site_info["Station"] == station_code]
@@ -435,22 +439,23 @@ def select_nearest_stations(st, epicenter_lat, epicenter_lon, n_stations=25):
             elev = station_data["Elevation"].values[0]
 
             distance = calculate_distance(epicenter_lat, epicenter_lon, lat, lon)
-            station_distances.append({
+            station_distances[station_code] = {
                 "station": station_code,
                 "distance": distance,
                 "latitude": lat,
                 "longitude": lon,
                 "elevation": elev
-            })
+            }
         except Exception as e:
             logger.warning(f"測站 {station_code} 資訊查詢失敗: {e}")
             continue
 
-    # 按距離排序並選擇最近的 n 個
-    station_distances.sort(key=lambda x: x["distance"])
-    selected_stations = station_distances[:n_stations]
+    # 轉換為列表並按距離排序，選擇最近的 n 個
+    station_list = list(station_distances.values())
+    station_list.sort(key=lambda x: x["distance"])
+    selected_stations = station_list[:n_stations]
 
-    logger.info(f"從 {len(station_distances)} 個輸入測站中選擇了最近的 {len(selected_stations)} 個")
+    logger.info(f"從 {len(station_list)} 個輸入測站中選擇了最近的 {len(selected_stations)} 個")
     return selected_stations