Add function for calling round on polygon points

geo_extensions/__init__.py

@@ -6,6 +6,7 @@
     densify_polygon,
     drop_z_coordinate,
     reverse_polygon,
+    round_points,
     simplify_polygon,
     split_polygon_on_antimeridian_ccw,
     split_polygon_on_antimeridian_fixed_size,
@@ -19,6 +20,7 @@
     "polygon_crosses_antimeridian_ccw",
     "polygon_crosses_antimeridian_fixed_size",
     "reverse_polygon",
+    "round_points",
     "simplify_polygon",
     "split_polygon_on_antimeridian_ccw",
     "split_polygon_on_antimeridian_fixed_size",

geo_extensions/transformations/__init__.py

@@ -39,13 +39,18 @@
     split_polygon_on_antimeridian_ccw,
     split_polygon_on_antimeridian_fixed_size,
 )
-from geo_extensions.transformations.general import drop_z_coordinate, reverse_polygon
+from geo_extensions.transformations.general import (
+    drop_z_coordinate,
+    reverse_polygon,
+    round_points,
+)
 from geo_extensions.transformations.geodetic import densify_polygon
 
 __all__ = (
     "densify_polygon",
     "drop_z_coordinate",
     "reverse_polygon",
+    "round_points",
     "simplify_polygon",
     "split_polygon_on_antimeridian_ccw",
     "split_polygon_on_antimeridian_fixed_size",

geo_extensions/transformations/general.py

@@ -2,9 +2,11 @@
 the polygons are using.
 """
 
+from typing import SupportsIndex
+
 from shapely.geometry import Polygon
 
-from geo_extensions.types import TransformationResult
+from geo_extensions.types import Transformation, TransformationResult
 
 
 def reverse_polygon(polygon: Polygon) -> TransformationResult:
@@ -22,3 +24,31 @@ def drop_z_coordinate(polygon: Polygon) -> TransformationResult:
             for interior in polygon.interiors
         ],
     )
+
+
+def round_points(ndigits: SupportsIndex) -> Transformation:
+    """Create a transformation that rounds polygon points to a given number of
+    digits.
+
+    :returns: a callable transformation using the passed parameters
+    """
+
+    def round_points_(polygon: Polygon) -> TransformationResult:
+        """Round the polygon's points."""
+        yield Polygon(
+            shell=(_round_coord(coord, ndigits) for coord in polygon.exterior.coords),
+            holes=[
+                # ruff hint
+                (_round_coord(coord, ndigits) for coord in interior.coords)
+                for interior in polygon.interiors
+            ],
+        )
+
+    return round_points_
+
+
+def _round_coord(
+    coords: tuple[float, ...],
+    ndigits: SupportsIndex,
+) -> tuple[float, ...]:
+    return tuple(round(x, ndigits) for x in coords)

tests/test_transformations.py

@@ -8,6 +8,7 @@
 from geo_extensions.transformations import (
     densify_polygon,
     drop_z_coordinate,
+    round_points,
     simplify_polygon,
     split_polygon_on_antimeridian_ccw,
     split_polygon_on_antimeridian_fixed_size,
@@ -236,6 +237,45 @@ def test_drop_z_coordinate_holes():
     ]
 
 
+def test_round_polygon_points():
+    polygon = Polygon(
+        shell=[
+            (20.123456789, 0.123456789),
+            (20.123456789, 10.123456789),
+            (20.123456789, 10.123456789),
+            (20.123456789, 0.123456789),
+            (20.123456789, 0.123456789),
+        ],
+        holes=[
+            [
+                (18.123456789, 2.123456789),
+                (18.123456789, 8.123456789),
+                (18.123456789, 8.123456789),
+                (18.123456789, 2.123456789),
+            ],
+        ],
+    )
+    assert list(round_points(3)(polygon)) == [
+        Polygon(
+            shell=[
+                (20.123, 0.123),
+                (20.123, 10.123),
+                (20.123, 10.123),
+                (20.123, 0.123),
+                (20.123, 0.123),
+            ],
+            holes=[
+                [
+                    (18.123, 2.123),
+                    (18.123, 8.123),
+                    (18.123, 8.123),
+                    (18.123, 2.123),
+                ],
+            ],
+        ),
+    ]
+
+
 @given(polygon=strategies.rectangles())
 @settings(suppress_health_check=[HealthCheck.filter_too_much])
 def test_split_polygon_on_antimeridian_ccw_returns_ccw(polygon):