[GH-3134] Implement distributed GeoPandas affine_transform

[jiayuasu]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide.

Is this PR related to a ticket?

• Yes, and the PR name follows the format [GH-XXX] my subject.
• Closes GeoPandas: implement distributed affine_transform #3134.
• Part of [EPIC] Implement More Geopandas Functions #2230.

What changes were proposed in this PR?

• Add GeoSeries.affine_transform(matrix) and GeoDataFrame geometry-column delegation.
• Execute 2D and 3D affine transforms as distributed ST_Affine Spark expressions without driver collection or Python row UDFs.
• Validate that matrices contain exactly 6 or 12 numeric coefficients, reject distributed/per-row inputs, and normalize valid coefficients to Python floats.
• Map GeoPandas' 12-value coefficient order explicitly to Sedona's Python wrapper order.
• Preserve index, CRS, SRID, nulls, typed empty geometries, and Z coordinates for 2D transforms.
• Document JTS/Shapely differences for mixed-dimensional collections, M/ZM ordinates, and NaN Z values.
• Add direct and GeoPandas parity coverage for 2D/3D transformations, geometry families, metadata, delegation, validation, and the coefficient-order regression.

How was this patch tested?

• python -m pytest -p no:cacheprovider -q tests/geopandas/test_geoseries.py tests/geopandas/test_match_geopandas_series.py -k affine_transform — 10 passed.
• Repository formatting, lint, security, and license hooks passed for all four changed files.

Did this PR include necessary documentation updates?

• Yes. The new public API includes its coefficient layouts, equations, example, and engine-compatibility notes in the API docstring.

[Copilot]

Pull request overview

Implements distributed GeoSeries.affine_transform(matrix) (and GeoDataFrame geometry-column delegation) by translating GeoPandas 2D/3D coefficient matrices into Sedona ST_Affine Spark expressions, with validation and parity tests to ensure correctness and metadata preservation.

Changes:

• Added GeoSeries.affine_transform(matrix) with validation, float normalization, and explicit 3D coefficient reordering for Sedona’s ST_Affine wrapper signature.
• Added GeoDataFrame/GeoSeries delegation entry and API docstring (including 2D/3D layouts and engine-difference notes).
• Added direct and GeoPandas-parity tests covering 2D/3D behavior, coefficient order regression, metadata/SRID/CRS handling, and validation errors.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
python/sedona/spark/geopandas/geoseries.py	Implements GeoSeries.affine_transform using distributed ST_Affine with 2D/3D handling and validation.
python/sedona/spark/geopandas/base.py	Adds delegated affine_transform API + docstring for GeoSeries/GeoDataFrame geometry-column delegation.
python/tests/geopandas/test_geoseries.py	Adds unit tests for metadata/SRID/CRS preservation, dimension handling, coefficient ordering, and validation.
python/tests/geopandas/test_match_geopandas_series.py	Adds GeoPandas parity tests for 2D parametrized matrices and a 3D case across geometry families.

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