From 8ebe58c8954cf0e58b245370dc4d3d5e93bdbbda Mon Sep 17 00:00:00 2001
From: Eric Duminil <eric.duminil@gmail.com>
Date: Sat, 19 Oct 2024 21:51:26 +0200
Subject: [PATCH] Define Transformer only once

---
 download_files_from_LGL_BW.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/download_files_from_LGL_BW.py b/download_files_from_LGL_BW.py
index 2c57c00..0d25e47 100644
--- a/download_files_from_LGL_BW.py
+++ b/download_files_from_LGL_BW.py
@@ -41,9 +41,11 @@ EXTRACT_REGIONS = True
 CITYGML_SERVER = "https://opengeodata.lgl-bw.de/data/lod2"
 RASTER = 2  # [km]
 BUNDESLAND = 'bw'
-WGS84 = CRS.from_epsg(4326)
 
+WGS84 = CRS.from_epsg(4326)
 LOCAL_CRS = CRS.from_epsg(32632)  # UTM32N, used in BW. https://epsg.io/32632
+TO_LOCAL_CRS = Transformer.from_crs(WGS84, LOCAL_CRS, always_xy=True)
+
 UTM = 32
 
 SCRIPT_DIR = Path(__file__).parent
@@ -62,10 +64,9 @@ if EXTRACT_REGIONS:
     GML_GLOB = "LoD2_*/LoD2_*.gml"
 
 
-def coordinates_to_grid(longitude: float, latitude: float, local_utm: CRS) -> tuple[int, int]:
+def coordinates_to_grid(longitude: float, latitude: float) -> tuple[int, int]:
     """Returns (x, y) of the tile on CITYGML_SERVER containing a given point."""
-    transformer = Transformer.from_crs(WGS84, local_utm, always_xy=True)
-    x, y = transformer.transform(longitude, latitude)
+    x, y = TO_LOCAL_CRS.transform(longitude, latitude)
     x = floor(x / 1000) - 1  # Odd x
     y = floor(y / 1000)  # Even y
     x -= x % RASTER
@@ -88,8 +89,8 @@ def wkt_polygon_to_grid_coords(location_name: str, wkt: str) -> tuple[int, int,
 
     print("%s (%.3f°N %.3f°E -> %.3f°N %.3f°E)" % (location_name, max_lat, min_lon, min_lat, max_lon))
 
-    x1, y1 = coordinates_to_grid(min_lon, min_lat, LOCAL_CRS)
-    x2, y2 = coordinates_to_grid(max_lon, max_lat, LOCAL_CRS)
+    x1, y1 = coordinates_to_grid(min_lon, min_lat)
+    x2, y2 = coordinates_to_grid(max_lon, max_lat)
 
     return (x1, x2, y1, y2)
 
@@ -181,8 +182,7 @@ def main(polygons: dict[str, str]) -> None:
 
 def show_coordinates(match):
     longitude, latitude = match.groups()
-    transformer = Transformer.from_crs(WGS84, LOCAL_CRS, always_xy=True)
-    x, y = transformer.transform(longitude, latitude)
+    x, y = TO_LOCAL_CRS.transform(longitude, latitude)
     return f"{x} {y}"
 
 def convert_wkt_to_local(wkt):
-- 
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