FIX: support Polygon/MultiPolygon in Voronoi graph builder (#688) by AliaaNasser7 · Pull Request #868 · pysal/libpysal

AliaaNasser7 · 2026-02-05T23:15:30Z

Description

I've updated the _voronoi builder to support polygonal geometries by using their centroids as generators. This proposes a practical resolution for #688 and bypasses the limitations of the current point-based validation.

Changes & Technical Implementation

Validation Bypass: The @_validate_coplanar decorator was causing indexing issues and attribute errors with Polygons. I moved the coplanar check inside the function and used centroid extraction to ensure the math stays consistent with the Voronoi logic.
Handling Geometry Types: I added a check for .centroid to handle GeoDataFrames directly. For other inputs, I'm using get_points_array with a fallback to reshape the array, ensuring we always pass an (n, 2) array to voronoi_frames.
Ghost Cell Filtering: Clipping often creates auxiliary cells that mess up the input-to-output mapping. I fixed this by explicitly mapping the heads_ix and tails_ix back to the original ids before returning the graph.
Kwargs: Passed **kwargs down to voronoi_frames to support parameters like shrink or buffer.

Verification

I tested this with a GeoDataFrame of adjacent polygons. The builder now correctly identifies neighbors and maintains the original index without crashing or throwing indexing errors.

Related to #688

…_frames

sjsrey · 2026-02-06T16:01:08Z

Thank you for this, but the changes are breaking the tests.
Please ensure the tests are passing prior to requesting a review of the PR.

AliaaNasser7 · 2026-02-06T18:46:18Z

Thank you for this, but the changes are breaking the tests. Please ensure the tests are passing prior to requesting a review of the PR.

Thanks for the feedback! I’m working through the failing tests.
I saw this is labeled as a good first issue, just wanted to check if you think it’s still a good starting point.

…sal#688)

codecov · 2026-02-09T15:48:34Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.5%. Comparing base (7304239) to head (35f2e72).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #868   +/-   ##
=====================================
  Coverage   85.5%   85.5%           
=====================================
  Files        151     151           
  Lines      16092   16141   +49     
=====================================
+ Hits       13758   13807   +49     
  Misses      2334    2334

Files with missing lines	Coverage Δ
libpysal/graph/_triangulation.py	`98.2% <100.0%> (+0.1%)`	⬆️
libpysal/graph/base.py	`96.6% <100.0%> (+<0.1%)`	⬆️
libpysal/graph/tests/test_triangulation.py	`98.9% <100.0%> (+0.1%)`	⬆️

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

AliaaNasser7 · 2026-02-09T18:39:31Z

Thank you for this, but the changes are breaking the tests. Please ensure the tests are passing prior to requesting a review of the PR.
The tests are now passing successfully. I fixed the issues that were breaking the tests earlier. Ready for review.

martinfleis

This completely missed the point of #688. Have a look at #678 which it refers to and try to understand what the aim was there. This PR does not support Polygons in Voronoi builders, it silently downcasts them to centroids.

AliaaNasser7 · 2026-02-20T00:37:04Z

This completely missed the point of #688. Have a look at #678 which it refers to and try to understand what the aim was there. This PR does not support Polygons in Voronoi builders, it silently downcasts them to centroids.

@martinfleis I reworked the PR completely ,instead of downcasting to centroids, _voronoi now passes geometries directly to voronoi_frames (which handles all geometry types since #678) and forwards segment/shrink kwargs.

martinfleis

It might be easier to keep the current _voronoi function intact with its coplanarity solutions and write a separate one for non-point geometry types. And just channel to the proper one when needed.

martinfleis · 2026-02-23T14:25:01Z

+    if coplanar == "jitter":
+        coords = shapely.get_coordinates(geoms)
+        coords = _jitter_geoms(coords, seed=seed)
+        geoms = geopandas.GeoSeries(
+            shapely.points(coords),
+            index=geoms.index if hasattr(geoms, "index") else None,


This is going to get very wrong when non-point geometry is given.

Please ensure that you write test suite alongside your contributions. Many of the issues you'd be able to catch yourself.

AliaaNasser7 · 2026-02-23T14:40:00Z

It might be easier to keep the current _voronoi function intact with its coplanarity solutions and write a separate one for non-point geometry types. And just channel to the proper one when needed.

Thank you for the guidance! ok, I will do the changes and also add proper tests this time.

AliaaNasser7 · 2026-03-03T01:03:34Z

It might be easier to keep the current _voronoi function intact with its coplanarity solutions and write a separate one for non-point geometry types. And just channel to the proper one when needed.

@martinfleis I reworked based on your suggestion, kept _voronoi intact and added a separate _voronoi_polygon for non-point geometries, build_triangulation now routes to the appropriate function based on geometry type.

martinfleis · 2026-04-24T14:05:14Z

+    heads, tails, weights = _voronoi_polygon(gdf, ids=ids)
+    assert len(np.unique(heads)) == 4


The tests should look like those above. Check the exact arrays, all of them.

martinfleis · 2026-04-24T14:05:22Z


 @pytest.mark.network
-def test_coplanar_jitter_voronoi(stores, stores_unique):
+def test_coplanar_jitter_voronoi(stores, stores_unique):  # edit


Suggested change

def test_coplanar_jitter_voronoi(stores, stores_unique): # edit

def test_coplanar_jitter_voronoi(stores, stores_unique):

martinfleis · 2026-04-24T14:05:54Z

 #### utilities


+def _voronoi_polygon(


this should not be under "utilities" but above.

martinfleis · 2026-04-24T14:06:20Z

+    heads = heads_ix
+    tails = tails_ix
+    weights = numpy.ones(len(heads_ix), dtype=numpy.int8)
+    return heads, tails, weights


Suggested change

heads = heads_ix

tails = tails_ix

weights = numpy.ones(len(heads_ix), dtype=numpy.int8)

return heads, tails, weights

weights = numpy.ones(len(heads_ix), dtype=numpy.int8)

return heads_ix, tails_ix, weights

martinfleis · 2026-04-24T14:06:50Z

+        ``method="voronoi"``. Supports ``segment`` (float) and ``shrink``
+        (float). Ignored for other methods.


Only for non-point inputs.

martinfleis · 2026-04-24T14:07:22Z


        Parameters
        ----------
        data : numpy.ndarray, geopandas.GeoSeries, geopandas.GeoDataFrame


This needs to be updated to also mention other geometry types.

martinfleis · 2026-04-24T14:09:26Z

-                decay=decay,
-                taper=taper,
-            )
+            if hasattr(data, "geom_type") and not set(data.geom_type) <= {"Point"}:


I think we should use shapely.get_type_id in here to check the geometry types for all inputs, not just geopandas ones.

AliaaNasser7 added 4 commits February 6, 2026 00:45

FIX: support all geometry types in Voronoi graph builder (pysal#688)

e2c0b20

feat: support polygon geometries in Voronoi graphs

cda89cd

FIX: filter unsupported kwargs and return computed weights in _voronoi

141a0c3

FIX: ensure seed is passed to jitter and filter coplanar from voronoi…

f01b968

…_frames

AliaaNasser7 added 2 commits February 7, 2026 14:54

Merge remote-tracking branch 'upstream/main' into fix-voronoi-polygons

83e0a18

Allow polygons in Voronoi and pass kwargs to voronoi_frames (fixes py…

c01eb6a

…sal#688)

STYLE: fix ruff formatting and imports

c9919f5

martinfleis requested changes Feb 9, 2026

View reviewed changes

AliaaNasser7 added 3 commits February 20, 2026 01:32

support all geometry types in Voronoi graph builder

b6a9b48

support all geometry types in Voronoi graph builder

bf46d2a

STYLE: fix import order

c315cf9

martinfleis reviewed Feb 23, 2026

View reviewed changes

ENH: add a separate function for non-point geometry types

35f2e72

martinfleis reviewed Apr 24, 2026

View reviewed changes

		heads, tails, weights = _voronoi_polygon(gdf, ids=ids)
		assert len(np.unique(heads)) == 4

	def test_coplanar_jitter_voronoi(stores, stores_unique): # edit
	def test_coplanar_jitter_voronoi(stores, stores_unique):

		``method="voronoi"``. Supports ``segment`` (float) and ``shrink``
		(float). Ignored for other methods.

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AliaaNasser7 commented Feb 5, 2026

Description

Changes & Technical Implementation

Verification

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sjsrey commented Feb 6, 2026

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AliaaNasser7 commented Feb 6, 2026

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AliaaNasser7 commented Feb 23, 2026

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