Inserts one or more points at specified positions on a LineString and returns the inserted points.
Syntax
geometry ST_LineInterpolatePoints(geometry aLinestring , float8 aFraction , boolean repeat);
geography ST_LineInterpolatePoints(geography aLinestring , float8 aFraction , boolean repeat);Parameters
|
Parameter |
Description |
|
aLinestring |
The target LineString object. |
|
aFraction |
The percentage along the line segment at which the point is inserted. It is a floating-point value from 0 to 1. |
|
repeat |
Specifies whether to insert points repeatedly. Default value: true. |
Description
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If repeat is set to true, a point is created at every specified distance.
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If the result contains zero or one point, it is returned as a Point. Otherwise, it is returned as a MultiPoint.
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This function supports 3D objects and does not delete the Z coordinate.
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This function supports M coordinates.
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When a geographic coordinate system is used, the calculation is based on spherical distance.
Examples
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Calculate the point coordinates at a specified fraction of the given line segment:
SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)', 0.20)); st_astext --------------------------------- MULTIPOINT(0 1,0 2,0 3,0 4,0 5) (1 row) -- gepgraphy SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)'::geography, 0.20)); st_astext ------------------------------------------------------------------------------------------------------- MULTIPOINT((0 1.00002443285827),(0 2.00004274948544),(0 3.00004884128919),(0 4.00003661494431),(0 5)) -
Without repeated insertion:
SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)', 0.20, false)); st_astext ------------ POINT(0 1) (1 row) SELECT ST_AsText(ST_LineInterpolatePoints('LINESTRING(0 0,0 5)'::geography, 0.20, false)); st_astext --------------------------- POINT(0 1.00002443285827) (1 row)