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-----------------------------------------------------------------------
-- ST_MultiBandMapAlgebra
-- Return the same map algebra expression to all the band of a raster.
-----------------------------------------------------------------------
CREATE OR REPLACE FUNCTION ST_MultiBandMapAlgebra(rast1 raster,
rast2 raster,
expression text,
extentexpr text)
RETURNS raster AS
$$
DECLARE
numband int;
newrast raster;
pixeltype text;
nodataval float;
BEGIN
numband := ST_NumBands(rast1);
IF numband != ST_NumBands(rast2) THEN
RAISE EXCEPTION 'ST_MultiBandMapAlgebra: Rasters do not have the same number of band';
END IF;
newrast := ST_MakeEmptyRaster(rast1);
FOR b IN 1..numband LOOP
pixeltype := ST_BandPixelType(rast1, b);
nodataval := ST_BandNodataValue(rast1, b);
newrast := ST_AddBand(newrast, NULL, ST_MapAlgebraExpr(rast1, b, rast2, b, expression, pixeltype, extentexpr, nodataval), 1);
END LOOP;
END;
$$
LANGUAGE 'plpgsql';
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