Name
GetNodeByPoint — Finds the node-id of a node at a point location.
Synopsis
integer GetNodeByPoint(varchar atopology, geometry apoint, float8 tol1);
설명
Retrieves the id of a node at a point location.
The function returns an integer (id-node) given a topology, a POINT and a tolerance. If tolerance = 0 means exact intersection, otherwise retrieves the node from an interval.
If apoint doesn't intersect a node, returns 0 (zero).
If use tolerance > 0 and there is more than one node near the point then an exception is thrown.
![[Note]](../images/note.png)
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이 함수는 tolerance = 0일 경우 ST_Intersects를, 그렇지 않을 경우 ST_DWithin을 이용합니다. |
GEOS 모듈로 실행
2.0.0 버전부터 사용할 수 있습니다.
예시
다음 예시들은 AddEdge 에서 생성한 경계선들을 사용합니다.
SELECT topology.GetNodeByPoint('ma_topo',geom, 1) As nearnode
FROM ST_GeomFromEWKT('SRID=26986;POINT(227591.9 893900.4)') As geom;
nearnode
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2
SELECT topology.GetNodeByPoint('ma_topo',geom, 1000) As too_much_tolerance
FROM ST_GeomFromEWKT('SRID=26986;POINT(227591.9 893900.4)') As geom;
----get error--
ERROR: Two or more nodes found