feat(c/sedona-geos): Implement ST_SimplifyPreserveTopology using geos (#243)

joonaspessi · web-flow · commit 8e6234c7401f · 2025-10-26T20:31:56.000-05:00
diff --git a/c/sedona-geos/src/lib.rs b/c/sedona-geos/src/lib.rs
@@ -31,5 +31,6 @@ mod st_isvalid;
 mod st_isvalidreason;
 mod st_length;
 mod st_perimeter;
+mod st_simplifypreservetopology;
 mod st_unaryunion;
 pub mod wkb_to_geos;
diff --git a/c/sedona-geos/src/register.rs b/c/sedona-geos/src/register.rs
@@ -21,7 +21,9 @@ use crate::{
     st_centroid::st_centroid_impl, st_convexhull::st_convex_hull_impl, st_dwithin::st_dwithin_impl,
     st_isring::st_is_ring_impl, st_issimple::st_is_simple_impl, st_isvalid::st_is_valid_impl,
     st_isvalidreason::st_is_valid_reason_impl, st_length::st_length_impl,
-    st_perimeter::st_perimeter_impl, st_unaryunion::st_unary_union_impl,
+    st_perimeter::st_perimeter_impl,
+    st_simplifypreservetopology::st_simplify_preserve_topology_impl,
+    st_unaryunion::st_unary_union_impl,
 };
 
 use crate::binary_predicates::{
@@ -57,12 +59,14 @@ pub fn scalar_kernels() -> Vec<(&'static str, ScalarKernelRef)> {
         ("st_length", st_length_impl()),
         ("st_overlaps", st_overlaps_impl()),
         ("st_perimeter", st_perimeter_impl()),
+        (
+            "st_simplifypreservetopology",
+            st_simplify_preserve_topology_impl(),
+        ),
         ("st_symdifference", st_sym_difference_impl()),
         ("st_touches", st_touches_impl()),
         ("st_unaryunion", st_unary_union_impl()),
         ("st_union", st_union_impl()),
         ("st_within", st_within_impl()),
-        ("st_crosses", st_crosses_impl()),
-        ("st_overlaps", st_overlaps_impl()),
     ]
 }
diff --git a/c/sedona-geos/src/st_simplifypreservetopology.rs b/c/sedona-geos/src/st_simplifypreservetopology.rs
@@ -0,0 +1,233 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::sync::Arc;
+
+use arrow_array::builder::BinaryBuilder;
+use arrow_schema::DataType;
+use datafusion_common::cast::as_float64_array;
+use datafusion_common::error::Result;
+use datafusion_common::DataFusionError;
+use datafusion_expr::ColumnarValue;
+use geos::Geom;
+use sedona_expr::scalar_udf::{ScalarKernelRef, SedonaScalarKernel};
+use sedona_geometry::wkb_factory::WKB_MIN_PROBABLE_BYTES;
+use sedona_schema::{
+    datatypes::{SedonaType, WKB_GEOMETRY},
+    matchers::ArgMatcher,
+};
+
+use crate::executor::GeosExecutor;
+
+/// ST_SimplifyPreserveTopology() implementation using the geos crate
+pub fn st_simplify_preserve_topology_impl() -> ScalarKernelRef {
+    Arc::new(STSimplifyPreserveTopology {})
+}
+
+#[derive(Debug)]
+struct STSimplifyPreserveTopology {}
+
+impl SedonaScalarKernel for STSimplifyPreserveTopology {
+    fn return_type(&self, args: &[SedonaType]) -> Result<Option<SedonaType>> {
+        let matcher = ArgMatcher::new(
+            vec![ArgMatcher::is_geometry(), ArgMatcher::is_numeric()],
+            WKB_GEOMETRY,
+        );
+
+        matcher.match_args(args)
+    }
+
+    fn invoke_batch(
+        &self,
+        arg_types: &[SedonaType],
+        args: &[ColumnarValue],
+    ) -> Result<ColumnarValue> {
+        let executor = GeosExecutor::new(arg_types, args);
+
+        let tolerance_value = args[1]
+            .cast_to(&DataType::Float64, None)?
+            .to_array(executor.num_iterations())?;
+        let tolerance_array = as_float64_array(&tolerance_value)?;
+
+        let mut tolerance_iter = tolerance_array.iter();
+
+        let mut builder = BinaryBuilder::with_capacity(
+            executor.num_iterations(),
+            WKB_MIN_PROBABLE_BYTES * executor.num_iterations(),
+        );
+
+        executor.execute_wkb_void(|wkb| {
+            match (wkb, tolerance_iter.next().unwrap()) {
+                (Some(wkb), Some(tolerance)) => {
+                    invoke_scalar(&wkb, tolerance, &mut builder)?;
+                    builder.append_value([]);
+                }
+                _ => builder.append_null(),
+            }
+            Ok(())
+        })?;
+
+        executor.finish(Arc::new(builder.finish()))
+    }
+}
+
+fn invoke_scalar(
+    geos_geom: &geos::Geometry,
+    tolerance: f64,
+    writer: &mut impl std::io::Write,
+) -> Result<()> {
+    let geometry = geos_geom
+        .topology_preserve_simplify(tolerance)
+        .map_err(|e| DataFusionError::Execution(format!("Failed to simplify geometry: {e}")))?;
+
+    let wkb = geometry
+        .to_wkb()
+        .map_err(|e| DataFusionError::Execution(format!("Failed to convert to wkb: {e}")))?;
+
+    writer.write_all(wkb.as_ref())?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use datafusion_common::ScalarValue;
+    use rstest::rstest;
+    use sedona_expr::scalar_udf::SedonaScalarUDF;
+    use sedona_schema::datatypes::{WKB_GEOMETRY, WKB_VIEW_GEOMETRY};
+    use sedona_testing::compare::assert_array_equal;
+    use sedona_testing::create::create_array;
+    use sedona_testing::testers::ScalarUdfTester;
+
+    use super::*;
+
+    #[rstest]
+    fn udf(#[values(WKB_GEOMETRY, WKB_VIEW_GEOMETRY)] sedona_type: SedonaType) {
+        let udf = SedonaScalarUDF::from_kernel(
+            "st_simplifypreservetopology",
+            st_simplify_preserve_topology_impl(),
+        );
+        let tester = ScalarUdfTester::new(
+            udf.into(),
+            vec![sedona_type.clone(), SedonaType::Arrow(DataType::Float64)],
+        );
+        tester.assert_return_type(WKB_GEOMETRY);
+
+        // Should remove the point (0 10)
+        let result = tester
+            .invoke_scalar_scalar("LINESTRING(0 0, 0 10, 0 51, 50 20, 30 20, 7 32)", 2.0)
+            .unwrap();
+        tester.assert_scalar_result_equals(result, "LINESTRING(0 0,0 51,50 20,30 20,7 32)");
+
+        // Short linestring should preserve endpoints
+        let result = tester
+            .invoke_scalar_scalar("LINESTRING(0 0,0 10)", 2.0)
+            .unwrap();
+        tester.assert_scalar_result_equals(result, "LINESTRING(0 0,0 10)");
+
+        // Null geometry
+        let result = tester.invoke_scalar_scalar(ScalarValue::Null, 1.0).unwrap();
+        assert!(result.is_null());
+
+        // Null tolerance
+        let result = tester
+            .invoke_scalar_scalar("LINESTRING(0 0,0 10)", ScalarValue::Null)
+            .unwrap();
+        assert!(result.is_null());
+
+        // Array processing with tolerance 2.0
+        let input_wkt_t2 = vec![
+            Some("LINESTRING(0 0, 0 10, 0 51, 50 20, 30 20, 7 32)"),
+            Some("POLYGON((0 0, 0 10, 0 11, 0 20, 10 20, 10 0, 0 0))"),
+            Some("LINESTRING EMPTY"),
+            Some("POINT EMPTY"),
+            Some("POLYGON EMPTY"),
+            None,
+        ];
+
+        let expected_t2 = create_array(
+            &[
+                Some("LINESTRING(0 0,0 51,50 20,30 20,7 32)"),
+                Some("POLYGON((0 0,0 20,10 20,10 0,0 0))"),
+                Some("LINESTRING EMPTY"),
+                Some("POINT EMPTY"),
+                Some("POLYGON EMPTY"),
+                None,
+            ],
+            &WKB_GEOMETRY,
+        );
+        assert_array_equal(
+            &tester.invoke_wkb_array_scalar(input_wkt_t2, 2.0).unwrap(),
+            &expected_t2,
+        );
+
+        // Array processing with tolerance 20.0
+        let input_wkt_t20 = vec![
+            Some("LINESTRING(0 0,0 10)"),
+            Some("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0),(5 5, 5 6, 6 6, 8 5, 5 5))"),
+            Some("MULTIPOLYGON(((100 100, 100 130, 130 130, 130 100, 100 100)),((0 0, 10 0, 10 10, 0 10, 0 0),(5 5, 5 6, 6 6, 8 5, 5 5)))"),
+        ];
+
+        let expected_t20 = create_array(
+            &[
+                Some("LINESTRING(0 0,0 10)"),
+                Some("POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,5 6,8 5,5 5))"),
+                Some("MULTIPOLYGON(((100 100,100 130,130 130,130 100,100 100)),((0 0,10 0,10 10,0 10,0 0),(5 5,5 6,8 5,5 5)))"),
+            ],
+            &WKB_GEOMETRY,
+        );
+        assert_array_equal(
+            &tester.invoke_wkb_array_scalar(input_wkt_t20, 20.0).unwrap(),
+            &expected_t20,
+        );
+
+        // Test array tolerance input - same geometry with different tolerance values
+        let input_wkt_array = vec![
+            Some("LINESTRING (0 0, 0 10, 0 51, 50 20, 30 20, 7 32)"),
+            Some("LINESTRING (0 0, 0 10, 0 51, 50 20, 30 20, 7 32)"),
+            Some("LINESTRING (0 0, 0 10, 0 51, 50 20, 30 20, 7 32)"),
+            None,
+        ];
+
+        use arrow_array::Float64Array;
+        let tolerance_array: Arc<Float64Array> = Arc::new(Float64Array::from(vec![
+            Some(2.0),
+            Some(10.0),
+            Some(50.0),
+            Some(5.0),
+        ]));
+
+        let expected_array = create_array(
+            &[
+                Some("LINESTRING (0 0, 0 51, 50 20, 30 20, 7 32)"), // Tolerance 2.0
+                Some("LINESTRING (0 0, 0 51, 50 20, 7 32)"),        // Tolerance 10.0
+                Some("LINESTRING (0 0, 7 32)"),                     // Tolerance 50.0
+                None,
+            ],
+            &WKB_GEOMETRY,
+        );
+
+        assert_array_equal(
+            &tester
+                .invoke_arrays(vec![
+                    create_array(&input_wkt_array, &sedona_type),
+                    tolerance_array,
+                ])
+                .unwrap(),
+            &expected_array,
+        );
+    }
+}
diff --git a/python/sedonadb/tests/functions/test_functions.py b/python/sedonadb/tests/functions/test_functions.py
@@ -1399,3 +1399,49 @@ def test_st_isvalidreason(eng, geom, expected):
     else:
         query = f"SELECT ST_IsValidReason({geom_or_null(geom)})"
         eng.assert_query_result(query, expected)
+
+
+@pytest.mark.parametrize("eng", [SedonaDB, PostGIS])
+@pytest.mark.parametrize(
+    ("geom", "tolerance", "expected"),
+    [
+        # removes intermediate point
+        (
+            "LINESTRING (0 0, 0 10, 0 51, 50 20, 30 20, 7 32)",
+            2,
+            "LINESTRING (0 0, 0 51, 50 20, 30 20, 7 32)",
+        ),
+        # Short linestring preserves endpoints
+        (
+            "LINESTRING (0 0, 0 10)",
+            20,
+            "LINESTRING (0 0, 0 10)",
+        ),
+        # Null handling
+        (None, 2, None),
+        (None, None, None),
+        ("LINESTRING (0 0, 0 10)", None, None),
+        # Empty geometries
+        ("LINESTRING EMPTY", 2, "LINESTRING EMPTY"),
+        ("POINT EMPTY", 2, "POINT (nan nan)"),
+        ("POLYGON EMPTY", 2, "POLYGON EMPTY"),
+        #  inner ring simplified
+        (
+            "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0), (5 5, 5 6, 6 6, 8 5, 5 5))",
+            20,
+            "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0), (5 5, 5 6, 8 5, 5 5))",
+        ),
+        # second polygon's inner ring simplified
+        (
+            "MULTIPOLYGON (((100 100, 100 130, 130 130, 130 100, 100 100)), ((0 0, 10 0, 10 10, 0 10, 0 0), (5 5, 5 6, 6 6, 8 5, 5 5)))",
+            20,
+            "MULTIPOLYGON (((100 100, 100 130, 130 130, 130 100, 100 100)), ((0 0, 10 0, 10 10, 0 10, 0 0), (5 5, 5 6, 8 5, 5 5)))",
+        ),
+    ],
+)
+def test_st_simplifypreservetopology(eng, geom, tolerance, expected):
+    eng = eng.create_or_skip()
+    eng.assert_query_result(
+        f"SELECT ST_SimplifyPreserveTopology({geom_or_null(geom)}, {val_or_null(tolerance)})",
+        expected,
+    )
