ST_LocateAlong

Determine which elements have a particular m (measure) coordinate.

This function operates only for cartesian coordinates.

Syntax

ST_LocateAlong(geo, m);

geo: The input points, multipoint, linestring, or multilinestring geometry.
Type: VARCHAR(ANY)
m: The value of the m coordinate that is to be matched.
Type: DOUBLE

Returns

A value of type VARCHAR(ANY) that contains a geometry of the same type as the input geometry, and whose vertices are the subset of the vertices of the input geometry that have the specified m coordinate. If the input geometry does not contain any such entries, an empty geometry collection is returned.

Examples

SELECT inza..ST_AsText(inza..ST_LocateAlong(inza..ST_WKTToSQL('
        MULTIPOINT (0 0 0 4, 100 0 0 5, 100 100 5 6, 0 100 7 8, 1 0 9 5)'), 5));
 
ST_ASTEXT
---------
MULTIPOINT ZM (100 0 0 5, 1 0 9 5)
(1 row)