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DistanceOp::distance(): make it return +inf instead of 0 if one of the geometry is empty #1345

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Merged
rouault merged 2 commits into from
Jan 24, 2026
+34 −23
Merged

DistanceOp::distance(): make it return +inf instead of 0 if one of the geometry is empty #1345

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DistanceOp::distance(): make it return NaN instead of 0 if one of the…
rouault Dec 16, 2025
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DistanceOp::distance(): make it return inf instead of 0 if one of the…
rouault Dec 18, 2025
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7 changes: 4 additions & 3 deletions capi/geos_c.h.in
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Original file line number Diff line number Diff line change
Expand Up @@ -3387,7 +3387,7 @@ extern char GEOS_DLL GEOSisSimple(const GEOSGeometry* g);
* In one step, calculate and return whether a geometry is simple
* and one more more points at which the geometry self-intersects
* at interior points.
* Caller has the responsibility to destroy 'location' with
* Caller has the responsibility to destroy 'location' with
* GEOSGeom_destroy()
*
* \param g The geometry to test
Expand Down Expand Up @@ -3631,7 +3631,8 @@ extern int GEOS_DLL GEOSGeomGetLength(
* Calculate the distance between two geometries.
* \param[in] g1 Input geometry
* \param[in] g2 Input geometry
* \param[out] dist Pointer to be filled in with distance result
* \param[out] dist Pointer to be filled in with distance result. Positive
* infinity is returned if one of the geometry is empty.
* \return 1 on success, 0 on exception.
* \since 2.2
*/
Expand Down Expand Up @@ -5462,7 +5463,7 @@ extern char GEOS_DLL GEOSIntersects(const GEOSGeometry* g1, const GEOSGeometry*
extern char GEOS_DLL GEOSCrosses(const GEOSGeometry* g1, const GEOSGeometry* g2);

/**
* Tests if geometry g1 is completely within g2,
* Tests if geometry g1 is completely within g2,
* but not wholly contained in the boundary of g2.
* \param g1 Input geometry
* \param g2 Input geometry
Expand Down
5 changes: 3 additions & 2 deletions src/operation/distance/DistanceOp.cpp
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Expand Up @@ -36,6 +36,7 @@
#include <geos/util/IllegalArgumentException.h>
#include <geos/util.h>

#include <limits>
#include <vector>
#include <iostream>

Expand Down Expand Up @@ -97,7 +98,7 @@ DistanceOp::DistanceOp(const Geometry& g0, const Geometry& g1, double tdist)
/**
* Report the distance between the closest points on the input geometries.
*
* @return the distance between the geometries
* @return the distance between the geometries, or positive infinity if one of them is empty.
*/
double
DistanceOp::distance()
Expand All @@ -111,7 +112,7 @@ DistanceOp::distance()
throw IllegalArgumentException("null geometries are not supported");
}
if(geom[0]->isEmpty() || geom[1]->isEmpty()) {
return 0.0;
return std::numeric_limits<double>::infinity();
}
if(geom[0]->getGeometryTypeId() == GEOS_POINT && geom[1]->getGeometryTypeId() == GEOS_POINT) {
return static_cast<const Point*>(geom[0])->getCoordinate()->distance(*static_cast<const Point*>(geom[1])->getCoordinate());
Expand Down
19 changes: 9 additions & 10 deletions tests/unit/operation/distance/DistanceOpTest.cpp
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Expand Up @@ -228,7 +228,7 @@ void object::test<8>

DistanceOp dist(g0.get(), g1.get());

ensure_equals(dist.distance(), 0);
ensure(std::isinf(dist.distance()));

ensure(dist.nearestPoints() == nullptr);
}
Expand Down Expand Up @@ -416,7 +416,7 @@ void object::test<16>

DistanceOp dist(g0.get(), g1.get());

ensure_equals(dist.distance(), 0);
ensure(std::isinf(dist.distance()));

ensure(dist.nearestPoints() == nullptr);
}
Expand Down Expand Up @@ -497,7 +497,7 @@ void object::test<19>
ensure(g1->isValid());
ensure(g2->isValid());

ensure_equals(g1->distance(g2.get()), 0);
ensure(std::isinf(g1->distance(g2.get())));
}

// Test case reported in Shapely
Expand Down Expand Up @@ -580,7 +580,6 @@ void object::test<22>()
ensure_equals(g2->distance(g1.get()), 1);
}

// Empty is same as empty so zero...?
template<>
template<>
void object::test<23>()
Expand All @@ -589,8 +588,8 @@ void object::test<23>()
auto g2 = wktreader.read("LINESTRING EMPTY");

ensure(g1 != nullptr && g2 != nullptr);
ensure_equals(g1->distance(g2.get()), 0);
ensure_equals(g2->distance(g1.get()), 0);
ensure(std::isinf(g1->distance(g2.get())));
ensure(std::isinf(g2->distance(g1.get())));
}

template<>
Expand All @@ -601,8 +600,8 @@ void object::test<24>()
auto g2 = wktreader.read("LINESTRING EMPTY");

ensure(g1 != nullptr && g2 != nullptr);
ensure_equals(g1->distance(g2.get()), 0);
ensure_equals(g2->distance(g1.get()), 0);
ensure(std::isinf(g1->distance(g2.get())));
ensure(std::isinf(g2->distance(g1.get())));
}

// But ignore empty if there's a real distance?
Expand Down Expand Up @@ -638,8 +637,8 @@ void object::test<27>()
auto g2 = wktreader.read("GEOMETRYCOLLECTION(POINT(1 0))");

ensure(g1 != nullptr && g2 != nullptr);
ensure_equals(g1->distance(g2.get()), 0);
ensure_equals(g2->distance(g1.get()), 0);
ensure(std::isinf(g1->distance(g2.get())));
ensure(std::isinf(g2->distance(g1.get())));
}


Expand Down
14 changes: 12 additions & 2 deletions tests/xmltester/XMLTester.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -894,8 +894,12 @@ Test::checkResult( bool result )
void
Test::checkResult( double result)
{
char* rest;
double expectedRes = std::strtod(opResult.c_str(), &rest);
char* rest = nullptr;
const double expectedRes = (opResult == "NaN" || opResult == "nan") ?
std::numeric_limits<double>::quiet_NaN() :
(opResult == "Inf" || opResult == "inf") ?
std::numeric_limits<double>::infinity() :
std::strtod(opResult.c_str(), &rest);
if(rest == opResult.c_str()) {
throw std::runtime_error("malformed testcase: missing expected double value");
}
Expand All @@ -904,6 +908,12 @@ Test::checkResult( double result)
isSuccess = true;
}
}
else if (std::isnan(expectedRes)) {
isSuccess = std::isnan(result);
}
else if( expectedRes == result ) {
isSuccess = true;
}
else {
if (std::abs(expectedRes - result) / expectedRes < 1e-3) {
isSuccess = true;
Expand Down
12 changes: 6 additions & 6 deletions tests/xmltester/tests/general/TestDistance.xml
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Expand Up @@ -4,8 +4,8 @@
<desc>PeP - point to an empty point</desc>
<a> POINT(10 10) </a>
<b> POINT EMPTY </b>
<test><op name="distance" arg1="A" arg2="B"> 0.0 </op></test>
<test><op name="distance" arg1="B" arg2="A"> 0.0 </op></test>
<test><op name="distance" arg1="A" arg2="B"> inf </op></test>
<test><op name="distance" arg1="B" arg2="A"> inf </op></test>
</case>

<case>
Expand Down Expand Up @@ -36,8 +36,8 @@
<desc>LL - line to empty line</desc>
<a> LINESTRING (0 0, 0 10) </a>
<b> LINESTRING EMPTY </b>
<test><op name="distance" arg1="A" arg2="B"> 0.0 </op></test>
<test><op name="distance" arg1="B" arg2="A"> 0.0 </op></test>
<test><op name="distance" arg1="A" arg2="B"> inf </op></test>
<test><op name="distance" arg1="B" arg2="A"> inf </op></test>
</case>

<case>
Expand Down Expand Up @@ -68,8 +68,8 @@
<desc>PA - point to empty polygon</desc>
<a> POINT (240 160) </a>
<b> POLYGON EMPTY </b>
<test><op name="distance" arg1="A" arg2="B" > 0.0 </op></test>
<test><op name="distance" arg1="B" arg2="A" > 0.0 </op></test>
<test><op name="distance" arg1="A" arg2="B" > inf </op></test>
<test><op name="distance" arg1="B" arg2="A" > inf </op></test>
</case>

<case>
Expand Down
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