added force_3d factory

pygeoif/factories.py

@@ -91,6 +91,40 @@ def force_2d(
     return shape(geometry)
 
 
+def force_3d(
+    context: Union[GeoType, GeoCollectionType],
+    z: float = 0,
+) -> Union[Geometry, GeometryCollection]:
+    """
+    Force the dimensionality of a geometry to 3D.
+
+    >>> force_3d(Point(0, 0))
+    Point(0, 0, 0)
+    >>> force_3d(Point(0, 0), 1)
+    Point(0, 0, 1)
+    >>> force_3d(Point(0, 0, 0))
+    Point(0, 0, 0)
+    >>> force_3d(LineString([(0, 0), (0, 1), (1, 1)]))
+    LineString(((0, 0, 0), (0, 1, 0), (1, 1, 0)))
+    """
+    geometry = context if isinstance(context, dict) else mapping(context)
+    if not geometry:
+        msg = "Object does not implement __geo_interface__"
+        raise TypeError(msg)
+    if geometry["type"] == "GeometryCollection":
+        return GeometryCollection(
+            force_3d(g, z)  # type: ignore [arg-type]
+            for g in geometry["geometries"]  # type: ignore [typeddict-item]
+        )
+
+    geometry["coordinates"] = move_coordinates(  # type: ignore [typeddict-unknown-key]
+        geometry["coordinates"],  # type: ignore [typeddict-item]
+        (0, 0, 0),
+        z,
+    )
+    return shape(geometry)
+
+
 def get_oriented_ring(ring: LineType, ccw: bool) -> LineType:  # noqa: FBT001
     s = 1.0 if ccw else -1.0
     return ring if signed_area(ring) / s >= 0 else ring[::-1]
@@ -364,6 +398,7 @@ def mapping(
 
 __all__ = [
     "force_2d",
+    "force_3d",
     "box",
     "from_wkt",
     "mapping",

tests/test_factories.py

@@ -143,6 +143,45 @@ def test_force_2d_nongeo() -> None:
     pytest.raises(AttributeError, factories.force_2d, (1, 2, 3))
 
 
+def test_force_3d_point() -> None:
+    p = geometry.Point(0, 0)
+    p3d = factories.force_3d(p)
+    assert p3d.x == 0
+    assert p3d.y == 0
+    assert p3d.z == 0
+    assert p3d.has_z
+
+
+def test_force_3d_collection() -> None:
+    gc = geometry.GeometryCollection(
+        [geometry.Point(-1, 1), geometry.Point(-2, 2)],
+    )
+    gc3d = factories.force_3d(gc)
+    assert list(gc3d.geoms) == [geometry.Point(-1, 1, 0), geometry.Point(-2, 2, 0)]
+
+
+def test_force_3d_point_with_z() -> None:
+    p = geometry.Point(0, 0, 1)
+    p3d = factories.force_3d(p)
+    assert p3d.x == 0
+    assert p3d.y == 0
+    assert p3d.z == 1
+    assert p3d.has_z
+
+
+def test_force_3d_point_noop() -> None:
+    p = geometry.Point(1, 2, 3)
+    p3d = factories.force_3d(p)
+    assert p3d.x == 1
+    assert p3d.y == 2
+    assert p3d.z == 3
+    assert p3d.has_z
+
+
+def test_force_3d_nongeo() -> None:
+    pytest.raises(AttributeError, factories.force_3d, (1, 2))
+
+
 def test_orient_true() -> None:
     ext = [(0, 0), (0, 2), (2, 2), (2, 0), (0, 0)]
     int_1 = [(0.5, 0.25), (1.5, 0.25), (1.5, 1.25), (0.5, 1.25), (0.5, 0.25)]