webui

collector/maidenhead.py~

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+"""
+Maidenhead locator helpers.
+
+latlon_to_subsquare(lat, lon) -> str       e.g. "JO78ai"
+subsquare_bounds(sq)          -> dict      {lat_min, lon_min, lat_max, lon_max}
+"""
+
+
+def latlon_to_subsquare(lat: float, lon: float) -> str:
+    """Convert WGS84 coordinates to 6-character Maidenhead subsquare."""
+    lon_n = lon + 180.0
+    lat_n = lat + 90.0
+
+    field_lon = int(lon_n / 20)
+    field_lat = int(lat_n / 10)
+    lon_n = lon_n % 20
+    lat_n = lat_n % 10
+
+    sq_lon = int(lon_n / 2)
+    sq_lat = int(lat_n / 1)
+    lon_n = (lon_n % 2) * 12
+    lat_n = (lat_n % 1) * 24
+
+    sub_lon = int(lon_n)
+    sub_lat = int(lat_n)
+
+    return (
+        chr(ord("A") + field_lon)
+        + chr(ord("A") + field_lat)
+        + str(sq_lon)
+        + str(sq_lat)
+        + chr(ord("a") + sub_lon)
+        + chr(ord("a") + sub_lat)
+    )
+
+
+def subsquare_bounds(sq: str) -> dict:
+    """
+    Return bounding box for a 6-character Maidenhead subsquare.
+    Each subsquare is 5' longitude ?? 2.5' latitude (~10 ?? 4.6 km in Sweden).
+    """
+    lon = (ord(sq[0]) - ord("A")) * 20.0
+    lat = (ord(sq[1]) - ord("A")) * 10.0
+    lon += int(sq[2]) * 2.0
+    lat += int(sq[3]) * 1.0
+    lon += (ord(sq[4]) - ord("a")) * (1.0 / 12.0)
+    lat += (ord(sq[5]) - ord("a")) * (1.0 / 24.0)
+    lon -= 180.0
+    lat -= 90.0
+    return {
+        "lat_min": lat,
+        "lon_min": lon,
+        "lat_max": lat + (1.0 / 24.0),
+        "lon_max": lon + (2.0 / 12.0),
+    }