Changes between Version 176 and Version 177 of WKTRaster/SpecificationWorking03

Timestamp:

11/11/11 11:16:13 (13 years ago)

Author:

dustymugs

Comment:

—

WKTRaster/SpecificationWorking03

@@ -1563 +1563 @@
 }}}
 
+This set of 2-raster ST_MapAlgebra functions require a user-provided function instead of expressions.  The user-provided function must receive three parameters (two double precision and one VARIADIC text array) and returns one double precision value.  A template for this user-provided function would be:
+
+{{{
+CREATE OR REPLACE FUNCTION userfunction(rast1 double precision, rast2 double precision, VARIADIC arg text[])
+        RETURNS double precision
+        AS $$
+        DECLARE
+        BEGIN
+                -- your code here
+        END;
+        $$
+        LANGUAGE 'plpgsql';
+}}}
+
+The function should be able to support a NULL input parameter.  The function may also be STRICT.
+
+1. ST_MapAlgebraFct(
+        rast1 raster, band1 integer,[[BR]]
+        rast2 raster, band2 integer,[[BR]]
+        userfunction regprocedure,[[BR]]
+        pixeltype text DEFAULT NULL, extenttype text DEFAULT 'INTERSECTION',[[BR]]
+        VARIADIC userargs text[] DEFAULT NULL
+)
+
+{{{
+ST_MapAlgebraFct(r1.rast, 1, r2.rast, 1, 'raster_mapalgebra_intersection(double precision, double precision, text[])'::regprocedure, '32BF', 'INTERSECTION')
+}}}
+
+2. ST_MapAlgebraFct(
+        rast1 raster,[[BR]]
+        rast2 raster,[[BR]]
+        userfunction regprocedure,[[BR]]
+        pixeltype text DEFAULT NULL, extenttype text DEFAULT 'INTERSECTION',[[BR]]
+        VARIADIC userargs text[] DEFAULT NULL
+)
+
+{{{
+ST_MapAlgebraFct(r1.rast, r2.rast, 'raster_mapalgebra_intersection(double precision, double precision, text[])'::regprocedure, '32BF', 'INTERSECTION')
+}}}
+
+3. ST_MapAlgebraFct(
+        rast1 raster,[[BR]]
+        rast2 raster,[[BR]]
+        userfunction regprocedure,[[BR]]
+        VARIADIC userargs text[]
+)
+
+{{{
+ST_MapAlgebraFct(r1.rast, r2.rast, 'raster_mapalgebra_intersection(double precision, double precision, text[])'::regprocedure, '32BF', 'INTERSECTION')
+}}}
 
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