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ST_Mean4ma
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ST_Mean4ma

12.13. Built-in Map Algebra Callback Functions

Name

ST_Mean4ma — Raster processing function that calculates the mean pixel value in a neighborhood.

Synopsis

float8 +`*`+ST_Mean4ma*(`float8[][] `matrix, text nodatamode, text[] VARIADIC args`)`;

double precision +`*`+ST_Mean4ma*(`double precision[][][] `value, integer[][] pos, text[] VARIADIC userargs`)`;

Description

Calculate the mean pixel value in a neighborhood of pixels.

For Variant 2, a substitution value for NODATA pixels can be specified by passing that value to userargs.

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

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

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: Variant 1

SELECT
    rid,
    st_value(
        st_mapalgebrafctngb(rast, 1, '32BF', 1, 1, 'st_mean4ma(float[][],text,text[])'::regprocedure, 'ignore', NULL), 2, 2
    )
FROM dummy_rast
WHERE rid = 2;
 rid |     st_value
-----+------------------
   2 | 253.222229003906
(1 row)

Examples: Variant 2

SELECT
    rid,
    st_value(
              ST_MapAlgebra(rast, 1, 'st_mean4ma(double precision[][][], integer[][], text[])'::regprocedure,'32BF', 'FIRST', NULL, 1, 1)
       ,  2, 2)
  FROM dummy_rast
   WHERE rid = 2;
 rid |     st_value
-----+------------------
   2 | 253.222229003906
(1 row)