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fixed logic

edited May 7, 2013 at 20:54

2.9k
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You haven't stated what output you want so an array of geometry should do:

CREATE OR REPLACE FUNCTION simplify_npoints(inGeom geometry, maxPoints integer) RETURNS geometry[] AS $$ DECLARE outGeom geometry[]=ARRAY[]::geometry[]; points geometry[]=ARRAY[]::geometry[]; counter integer:=0; BEGIN IF maxPoints=1 THEN RAISE EXCEPTION 'maxPoints must be >1. Split not possible'; END IF; FOR i IN 1..ST_NPoints(inGeom) LOOP counter:=counter+1; points := array_append(points, ST_PointN(inGeom,i)); IF counter=maxPoints THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); points := ARRAY[ST_PointN(inGeom,i)]; counter:=1; END IF; END LOOP; IF counter>1 THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); END IF; RETURN outGeom; END; $$ LANGUAGE plpgsql IMMUTABLE;

You haven't stated what output you want so an array of geometry should do:

CREATE OR REPLACE FUNCTION simplify_npoints(inGeom geometry, maxPoints integer) RETURNS geometry[] AS $$ DECLARE outGeom geometry[]=ARRAY[]::geometry[]; points geometry[]=ARRAY[]::geometry[]; counter integer:=0; BEGIN IF maxPoints=1 THEN RAISE EXCEPTION 'maxPoints must be >1. Split not possible'; END IF; FOR i IN 1..ST_NPoints(inGeom) LOOP counter:=counter+1; points := array_append(points, ST_PointN(inGeom,i)); IF counter=maxPoints THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); points := ARRAY[ST_PointN(inGeom,i)]; counter:=1; END IF; END LOOP; RETURN outGeom; END; $$ LANGUAGE plpgsql IMMUTABLE;

You haven't stated what output you want so an array of geometry should do:

CREATE OR REPLACE FUNCTION simplify_npoints(inGeom geometry, maxPoints integer) RETURNS geometry[] AS $$ DECLARE outGeom geometry[]=ARRAY[]::geometry[]; points geometry[]=ARRAY[]::geometry[]; counter integer:=0; BEGIN IF maxPoints=1 THEN RAISE EXCEPTION 'maxPoints must be >1. Split not possible'; END IF; FOR i IN 1..ST_NPoints(inGeom) LOOP counter:=counter+1; points := array_append(points, ST_PointN(inGeom,i)); IF counter=maxPoints THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); points := ARRAY[ST_PointN(inGeom,i)]; counter:=1; END IF; END LOOP; IF counter>1 THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); END IF; RETURN outGeom; END; $$ LANGUAGE plpgsql IMMUTABLE;

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answered May 5, 2013 at 15:56

Jakub Kania

2.9k
18
22

You haven't stated what output you want so an array of geometry should do:

CREATE OR REPLACE FUNCTION simplify_npoints(inGeom geometry, maxPoints integer) RETURNS geometry[] AS $$ DECLARE outGeom geometry[]=ARRAY[]::geometry[]; points geometry[]=ARRAY[]::geometry[]; counter integer:=0; BEGIN IF maxPoints=1 THEN RAISE EXCEPTION 'maxPoints must be >1. Split not possible'; END IF; FOR i IN 1..ST_NPoints(inGeom) LOOP counter:=counter+1; points := array_append(points, ST_PointN(inGeom,i)); IF counter=maxPoints THEN outgeom:=array_append(outGeom,ST_MakeLine(points)); points := ARRAY[ST_PointN(inGeom,i)]; counter:=1; END IF; END LOOP; RETURN outGeom; END; $$ LANGUAGE plpgsql IMMUTABLE;