Description

Calculate the number of unique pixel values in a neighborhood of pixels.

	This function is a specialized callback function for use as a callback parameter to ST_MapAlgebraFctNgb.

Availability: 2.0.0

Examples

SELECT 
    rid,
    st_value(
        st_mapalgebrafctngb(rast, 1, NULL, 1, 1, 'st_distinct4ma(float[][],text,text[])'::regprocedure, 'ignore', NULL), 2, 2
    ) 
FROM dummy_rast 
WHERE rid = 2;
 rid | st_value
-----+----------
   2 |        3
(1 row)
				

See Also

ST_MapAlgebraFctNgb, ST_Min4ma, ST_Max4ma, ST_Sum4ma, ST_Mean4ma, ST_Distinct4ma ST_StdDev4ma