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Function: _st_tpi4ma

Schema

public

Owner

albenard

Descriptions

There is no description for function _st_tpi4ma

Options

Definition

CREATE OR REPLACE FUNCTION public._st_tpi4ma (
 value double precision [],
 pos integer [],
 variadic userargs text [] = NULL::text[]
)
RETURNS double precision AS
$span$
DECLARE
x integer;
y integer;
z integer;

Z1 double precision;
Z2 double precision;
Z3 double precision;
Z4 double precision;
Z5 double precision;
Z6 double precision;
Z7 double precision;
Z8 double precision;
Z9 double precision;

tpi double precision;
mean double precision;
_value double precision[][][];
ndims int;
BEGIN
ndims := array_ndims(value);
-- add a third dimension if 2-dimension
IF ndims = 2 THEN
_value := public._ST_convertarray4ma(value);
ELSEIF ndims != 3 THEN
RAISE EXCEPTION 'First parameter of function must be a 3-dimension array';
ELSE
_value := value;
END IF;

-- only use the first raster passed to this function
IF array_length(_value, 1) > 1 THEN
RAISE NOTICE 'Only using the values from the first raster';
END IF;
z := array_lower(_value, 1);

IF (
array_lower(_value, 2) != 1 OR array_upper(_value, 2) != 3 OR
array_lower(_value, 3) != 1 OR array_upper(_value, 3) != 3
) THEN
RAISE EXCEPTION 'First parameter of function must be a 1x3x3 array with each of the lower bounds starting from 1';
END IF;

-- check that center pixel isn't NODATA
IF _value[z][2][2] IS NULL THEN
RETURN NULL;
-- substitute center pixel for any neighbor pixels that are NODATA
ELSE
FOR y IN 1..3 LOOP
FOR x IN 1..3 LOOP
IF _value[z][y][x] IS NULL THEN
_value[z][y][x] = _value[z][2][2];
END IF;
END LOOP;
END LOOP;
END IF;

-------------------------------------------------
--|   Z1= Z(-1,1) |  Z2= Z(0,1) | Z3= Z(1,1)  |--
-------------------------------------------------
--|   Z4= Z(-1,0) |  Z5= Z(0,0) | Z6= Z(1,0)  |--
-------------------------------------------------
--|   Z7= Z(-1,-1)|  Z8= Z(0,-1)|  Z9= Z(1,-1)|--
-------------------------------------------------

Z1 := _value[z][1][1];
Z2 := _value[z][2][1];
Z3 := _value[z][3][1];
Z4 := _value[z][1][2];
Z5 := _value[z][2][2];
Z6 := _value[z][3][2];
Z7 := _value[z][1][3];
Z8 := _value[z][2][3];
Z9 := _value[z][3][3];

mean := (Z1 + Z2 + Z3 + Z4 + Z6 + Z7 + Z8 + Z9)/8;
tpi := Z5-mean;

return tpi;
END;
$span$
LANGUAGE 'plpgsql'
IMMUTABLE
CALLED ON NULL INPUT
SECURITY INVOKER
COST 100;

This file was generated with SQL Manager for PostgreSQL (www.pgsqlmanager.com) at 26/02/2014 11:51