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[GH-2230] Add GeoSeries.shortest_line and GeoSeries.offset_curve #2828

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[GH-2230] Add GeoSeries.shortest_line and GeoSeries.offset_curve #2828

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f42265e
[GH-2230] Add GeoSeries.shortest_line and GeoSeries.offset_curve
jiayuasu Apr 7, 2026
647a25c
Fix offset_curve docstring: distance param is scalar only
jiayuasu Apr 7, 2026
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91 changes: 89 additions & 2 deletions python/sedona/spark/geopandas/base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -994,8 +994,50 @@ def extract_unique_points(self):
"""
return _delegate_to_geometry_column("extract_unique_points", self)

# def offset_curve(self, distance, quad_segs=8, join_style="round", mitre_limit=5.0):
# raise NotImplementedError("This method is not implemented yet.")
def offset_curve(self, distance, quad_segs=8, join_style="round", mitre_limit=5.0):
"""Returns a line at a given offset distance from each linear geometry.

Positive distance offsets to the left, negative to the right.

Parameters
----------
distance : float
The offset distance. Positive offsets to the left, negative to the
right.
quad_segs : int, default 8
Number of segments to approximate a quarter circle.
join_style : str, default "round"
Accepted values are "round", "mitre", and "bevel".

.. note::
``join_style`` and ``mitre_limit`` are accepted for API
compatibility but are currently ignored by Sedona's
``ST_OffsetCurve``.

mitre_limit : float, default 5.0
Limit on the mitre ratio.

Returns
-------
GeoSeries

Examples
--------
>>> from sedona.spark.geopandas import GeoSeries
>>> from shapely.geometry import LineString
>>> s = GeoSeries(
... [
... LineString([(0, 0), (10, 0)]),
... ]
... )
>>> s.offset_curve(1.0)
0 LINESTRING (0 1, 10 1)
dtype: geometry

"""
return _delegate_to_geometry_column(
"offset_curve", self, distance, quad_segs, join_style, mitre_limit
)

# @property
# def interiors(self):
Expand Down Expand Up @@ -2822,6 +2864,51 @@ def intersection(self, other, align=None):
"""
return _delegate_to_geometry_column("intersection", self, other, align)

def shortest_line(self, other, align=None):
"""Returns the shortest line between each geometry in the ``GeoSeries``
and `other`.

The resulting line starts on this geometry and ends on `other`.

The operation works on a 1-to-1 row-wise manner:

Parameters
----------
other : GeoSeries or geometric object
The GeoSeries (elementwise) or geometric object to find the
shortest line to.
align : bool | None (default None)
If True, automatically aligns GeoSeries based on their indices. None defaults to True.
If False, the order of elements is preserved.

Returns
-------
GeoSeries

Examples
--------
>>> from sedona.spark.geopandas import GeoSeries
>>> from shapely.geometry import Point, LineString
>>> s1 = GeoSeries(
... [
... Point(0, 0),
... LineString([(0, 0), (1, 0)]),
... ]
... )
>>> s2 = GeoSeries(
... [
... Point(1, 1),
... Point(0, 1),
... ]
... )
>>> s1.shortest_line(s2, align=False)
0 LINESTRING (0 0, 1 1)
1 LINESTRING (0 0, 0 1)
dtype: geometry

"""
return _delegate_to_geometry_column("shortest_line", self, other, align)

def snap(self, other, tolerance, align=None):
"""Snap the vertices and segments of the geometry to vertices of the reference.

Expand Down
21 changes: 19 additions & 2 deletions python/sedona/spark/geopandas/geoseries.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1058,8 +1058,13 @@ def extract_unique_points(self):
)

def offset_curve(self, distance, quad_segs=8, join_style="round", mitre_limit=5.0):
# Implementation of the abstract method.
raise NotImplementedError("This method is not implemented yet.")
# ST_OffsetCurve returns null for empty geometries, but GeoPandas returns LINESTRING EMPTY
empty_line = stc.ST_GeomFromText(F.lit("LINESTRING EMPTY"))
spark_col = F.when(
stf.ST_IsEmpty(self.spark.column),
empty_line,
).otherwise(stf.ST_OffsetCurve(self.spark.column, distance, quad_segs))
Comment on lines +1061 to +1066
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Copilot AI Apr 7, 2026

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offset_curve replaces empty input geometries with ST_GeomFromText('LINESTRING EMPTY'), which will have SRID=0. If the input GeoSeries has CRS set (via SRID), this can silently drop CRS for results (e.g., if the first non-null row is empty, GeoSeries.crs will become None). Consider constructing the empty geometry with the input SRID (e.g., pass ST_SRID(self.spark.column) as the srid arg to ST_GeomFromText, or ST_SetSRID on the empty geometry) so CRS/SRID is preserved even for empty rows.

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return self._query_geometry_column(spark_col, returns_geom=True)

@property
def interiors(self):
Expand Down Expand Up @@ -1528,6 +1533,18 @@ def intersection(
)
return result

def shortest_line(self, other, align=None) -> "GeoSeries":
other_series, extended = self._make_series_of_val(other)
align = False if extended else align

spark_expr = stf.ST_ShortestLine(F.col("L"), F.col("R"))
return self._row_wise_operation(
spark_expr,
other_series,
align=align,
returns_geom=True,
)

def snap(self, other, tolerance, align=None) -> "GeoSeries":
if not isinstance(tolerance, (float, int)):
raise NotImplementedError(
Expand Down
84 changes: 83 additions & 1 deletion python/tests/geopandas/test_geoseries.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1544,7 +1544,41 @@ def test_extract_unique_points(self):
self.check_sgpd_equals_gpd(df_result, expected)

def test_offset_curve(self):
pass
s = GeoSeries(
[
LineString([(0, 0), (0, 1), (1, 1)]),
LineString([(0, 0), (10, 0)]),
]
)

result = s.offset_curve(1.0)
expected = gpd.GeoSeries(
[
LineString([(0, 0), (0, 1), (1, 1)]),
LineString([(0, 0), (10, 0)]),
]
).offset_curve(1.0)
self.check_sgpd_equals_gpd(result, expected)

# Negative distance (right side)
result = s.offset_curve(-1.0)
expected = gpd.GeoSeries(
[
LineString([(0, 0), (0, 1), (1, 1)]),
LineString([(0, 0), (10, 0)]),
]
).offset_curve(-1.0)
self.check_sgpd_equals_gpd(result, expected)

# Check that GeoDataFrame works too
df_result = s.to_geoframe().offset_curve(1.0)
expected = gpd.GeoSeries(
[
LineString([(0, 0), (0, 1), (1, 1)]),
LineString([(0, 0), (10, 0)]),
]
).offset_curve(1.0)
self.check_sgpd_equals_gpd(df_result, expected)

def test_interiors(self):
pass
Expand Down Expand Up @@ -2599,6 +2633,54 @@ def test_snap(self):
df_result = s.to_geoframe().snap(s2, tolerance=1, align=False)
self.check_sgpd_equals_gpd(df_result, expected)

def test_shortest_line(self):
s1 = GeoSeries(
[
Point(0, 0),
LineString([(0, 0), (1, 0)]),
Polygon([(0, 0), (1, 0), (1, 1), (0, 1)]),
]
)
s2 = GeoSeries(
[
Point(1, 1),
Point(0, 1),
Point(2, 2),
]
)

result = s1.shortest_line(s2, align=False)
expected = gpd.GeoSeries(
[
LineString([(0, 0), (1, 1)]),
LineString([(0, 0), (0, 1)]),
LineString([(1, 1), (2, 2)]),
]
)
self.check_sgpd_equals_gpd(result, expected)

# Test with single geometry
result = s1.shortest_line(Point(1, 1))
expected = gpd.GeoSeries(
[
LineString([(0, 0), (1, 1)]),
LineString([(1, 0), (1, 1)]),
LineString([(1, 1), (1, 1)]),
]
)
self.check_sgpd_equals_gpd(result, expected)

# Test that GeoDataFrame works too
df_result = s1.to_geoframe().shortest_line(s2, align=False)
expected = gpd.GeoSeries(
[
LineString([(0, 0), (1, 1)]),
LineString([(0, 0), (0, 1)]),
LineString([(1, 1), (2, 2)]),
]
)
self.check_sgpd_equals_gpd(df_result, expected)

def test_intersection_all(self):
s = GeoSeries([box(0, 0, 2, 2), box(1, 1, 3, 3)])
result = s.intersection_all()
Expand Down
33 changes: 32 additions & 1 deletion python/tests/geopandas/test_match_geopandas_series.py
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Original file line number Diff line number Diff line change
Expand Up @@ -832,7 +832,21 @@ def test_extract_unique_points(self):
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

def test_offset_curve(self):
pass
for geom in self.geoms:
# offset_curve only works on linear geometries
if not all(
isinstance(g, (LineString, LinearRing, MultiLineString))
for g in geom
if not g.is_empty
):
continue
sgpd_result = GeoSeries(geom).offset_curve(1.0)
gpd_result = gpd.GeoSeries(geom).offset_curve(1.0)
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

sgpd_result = GeoSeries(geom).offset_curve(-0.5)
gpd_result = gpd.GeoSeries(geom).offset_curve(-0.5)
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

def test_interiors(self):
pass
Expand Down Expand Up @@ -1188,6 +1202,23 @@ def test_snap(self):
)
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

def test_shortest_line(self):
for geom, geom2 in self.pairs:
if self.contains_any_geom_collection(geom, geom2):
continue
sgpd_result = GeoSeries(geom).shortest_line(GeoSeries(geom2))
gpd_result = gpd.GeoSeries(geom).shortest_line(gpd.GeoSeries(geom2))
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

if len(geom) == len(geom2):
sgpd_result = GeoSeries(geom).shortest_line(
GeoSeries(geom2), align=False
)
gpd_result = gpd.GeoSeries(geom).shortest_line(
gpd.GeoSeries(geom2), align=False
)
self.check_sgpd_equals_gpd(sgpd_result, gpd_result)

def test_intersection_all(self):
pass

Expand Down
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