ST_Distinct4ma
Prev 6.13. Built-in Map Algebra Callback Functions Next

Name

ST_Distinct4ma — Raster processing function that calculates the number of unique pixel values in a neighborhood.

Synopsis

float8 ST_Distinct4ma(float8[][] matrix, text nodatamode, text[] VARIADIC args);

double precision ST_Distinct4ma(double precision[][][] value, integer[][] pos, text[] VARIADIC userargs);

Description

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

[Note]

Variant 1 is a specialized callback function for use as a callback parameter to ST_MapAlgebraFctNgb.

[Note]

Variant 2 is a specialized callback function for use as a callback parameter to ST_MapAlgebra (callback function version).

[Warning]

Use of Variant 1 is discouraged since ST_MapAlgebraFctNgb has been deprecated as of 2.1.0.

Availability: 2.0.0

Enhanced: 2.1.0 Addition of Variant 2

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_MapAlgebra (callback function version), ST_Min4ma, ST_Max4ma, ST_Sum4ma, ST_Mean4ma, ST_Distinct4ma, ST_StdDev4ma

Prev Up Next
ST_Union Home ST_InvDistWeight4ma