ST_ContainsProperly — Tests if every point of B lies in the interior of A
boolean ST_ContainsProperly(
geometry
geomA, geometry
geomB)
;
Returns true
if every point of B lies in the interior of A
(or equivalently, no point of B lies in the the boundary or exterior of A).
In mathematical terms: ST_ContainsProperly(A, B) ⇔ Int(A) ⋂ B = B
A contains B properly if the DE-9IM Intersection Matrix for the two geometries matches [T**FF*FF*]
A does not properly contain itself, but does contain itself.
A use for this predicate is computing the intersections of a set of geometries with a large polygonal geometry. Since intersection is a fairly slow operation, it can be more efficient to use containsProperly to filter out test geometries which lie fully inside the area. In these cases the intersection is known a priori to be exactly the original test geometry.
This function automatically includes a bounding box comparison
that makes use of any spatial indexes that are available on the geometries.
To avoid index use, use the function |
The advantage of this predicate over ST_Contains and ST_Intersects is that it can be computed more efficiently, with no need to compute topology at individual points. |
Performed by the GEOS module.
Availability: 1.4.0
Enhanced: 3.0.0 enabled support for |
Do not use this function with invalid geometries. You will get unexpected results. |
--a circle within a circle SELECT ST_ContainsProperly(smallc, bigc) As smallcontainspropbig, ST_ContainsProperly(bigc,smallc) As bigcontainspropsmall, ST_ContainsProperly(bigc, ST_Union(smallc, bigc)) as bigcontainspropunion, ST_Equals(bigc, ST_Union(smallc, bigc)) as bigisunion, ST_Covers(bigc, ST_ExteriorRing(bigc)) As bigcoversexterior, ST_ContainsProperly(bigc, ST_ExteriorRing(bigc)) As bigcontainsexterior FROM (SELECT ST_Buffer(ST_GeomFromText('POINT(1 2)'), 10) As smallc, ST_Buffer(ST_GeomFromText('POINT(1 2)'), 20) As bigc) As foo; --Result smallcontainspropbig | bigcontainspropsmall | bigcontainspropunion | bigisunion | bigcoversexterior | bigcontainsexterior ------------------+------------------+------------------+------------+-------------------+--------------------- f | t | f | t | t | f --example demonstrating difference between contains and contains properly SELECT ST_GeometryType(geomA) As geomtype, ST_Contains(geomA,geomA) AS acontainsa, ST_ContainsProperly(geomA, geomA) AS acontainspropa, ST_Contains(geomA, ST_Boundary(geomA)) As acontainsba, ST_ContainsProperly(geomA, ST_Boundary(geomA)) As acontainspropba FROM (VALUES ( ST_Buffer(ST_Point(1,1), 5,1) ), ( ST_MakeLine(ST_Point(1,1), ST_Point(-1,-1) ) ), ( ST_Point(1,1) ) ) As foo(geomA); geomtype | acontainsa | acontainspropa | acontainsba | acontainspropba --------------+------------+----------------+-------------+----------------- ST_Polygon | t | f | f | f ST_LineString | t | f | f | f ST_Point | t | t | f | f
ST_GeometryType, ST_Boundary, ST_Contains, ST_Covers, ST_CoveredBy, ST_Equals, ST_Relate, ST_Within