Update script to support parameters

Author: geographika

workshop/exercises/scripts/extents.py

@@ -1,30 +1,38 @@
-"""
-python /scripts/extents.py
-"""
-
-import mapscript
-
-mapfile = "/etc/mapserver/lakes.map"
-m = mapscript.mapObj(mapfile)
-
-lyr = m.getLayerByName("lakes")
-extent = lyr.getExtent()
-
-original_projection_code = m.getProjection()
-original_projection = mapscript.projectionObj(original_projection_code)
-
-webmercator = mapscript.projectionObj("epsg:3857")
-
-extent_string = f"[{extent.minx}, {extent.miny}, {extent.maxx}, {extent.maxy}]"
-print(extent_string)
-
-# reprojection is done in-place
-extent.project(original_projection, webmercator)
-
-extent_string = f"[{extent.minx}, {extent.miny}, {extent.maxx}, {extent.maxy}]"
-print(extent_string)
-
-center = f"[{(extent.maxx + extent.minx) / 2}, {(extent.maxy + extent.miny) / 2}]"
-print(center)
-
-print("Done!")
+"""
+python /scripts/extents.py --mapfile "/etc/mapserver/arcgis.map"
+"""
+
+import mapscript
+import argparse
+
+
+def get_extent_and_center(mapfile):
+    m = mapscript.mapObj(mapfile)
+    extent = m.extent
+
+    original_projection_code = m.getProjection()
+    original_projection = mapscript.projectionObj(original_projection_code)
+
+    webmercator = mapscript.projectionObj("epsg:3857")
+
+    extent_string = f"[{extent.minx}, {extent.miny}, {extent.maxx}, {extent.maxy}]"
+    print(f"Original extent {original_projection_code}: {extent_string}")
+
+    # reprojection is done in-place
+    extent.project(original_projection, webmercator)
+
+    extent_string = f"[{extent.minx}, {extent.miny}, {extent.maxx}, {extent.maxy}]"
+    print(f"New extent epsg:3857: {extent_string}")
+
+    center = f"[{(extent.maxx + extent.minx) / 2}, {(extent.maxy + extent.miny) / 2}]"
+    print(f"Center: {center}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Print map extent and center in WebMercator"
+    )
+    parser.add_argument("--mapfile", type=str, help="Path to the MapServer mapfile")
+    args = parser.parse_args()
+    get_extent_and_center(args.mapfile)
+    print("Done!")