GetEdgeByPoint
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## Name

GetEdgeByPoint — Finds the edge-id of an edge that intersects a given point.

## Synopsis

`integer GetEdgeByPoint(`varchar atopology, geometry apoint, float8 tol1`)`;

## Description

Retrieves the id of an edge that intersects a Point.

The function returns an integer (id-edge) given a topology, a POINT and a tolerance. If tolerance = 0 then the point has to intersect the edge.

If `apoint` doesn't intersect an edge, returns 0 (zero).

If use tolerance > 0 and there is more than one edge near the point then an exception is thrown.

If tolerance = 0, the function uses ST_Intersects otherwise uses ST_DWithin.

Performed by the GEOS module.

Availability: 2.0.0

## Examples

These examples use edges we created in AddEdge

    SELECT topology.GetEdgeByPoint('ma_topo',geom, 1) As with1mtol, topology.GetEdgeByPoint('ma_topo',geom,0) As withnotol
    FROM ST_GeomFromEWKT('SRID=26986;POINT(227622.6 893843)') As geom;
     with1mtol | withnotol
    -----------+-----------
             2 |         0

    SELECT topology.GetEdgeByPoint('ma_topo',geom, 1) As nearnode
    FROM ST_GeomFromEWKT('SRID=26986;POINT(227591.9 893900.4)') As geom;

    -- get error --
    ERROR:  Two or more edges found

## See Also

AddEdge, GetNodeByPoint, GetFaceByPoint

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