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ST_Distinct4ma

ST_Distinct4ma
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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 .

[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 , ST_Min4ma , ST_Max4ma , ST_Sum4ma , ST_Mean4ma , ST_Distinct4ma , ST_StdDev4ma

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