Обсуждение: Looking for a way to sum integer arrays....
I'd like to be able to sum up an integer array. Like so:
{3,2,1} + {0,2,2} ------- {3,4,3}
The following solution I've been hacking on works, although I think it
is far from "ideal". Is there a built in way to sum up arrays? If not,
is there a better way than my crude method? I have tested this on 7.4
and 8.0. I'd also be appreciate if any insight on why my aggregate
fails to work when I have an empty initcondition. P.S. I have never
written an aggregate and I was lost trying to follow the complex_sum
example in the docs.
---------------------------------------------
CREATE OR REPLACE FUNCTION sum_intarray(INTEGER[],INTEGER[]) RETURNS
INTEGER[] LANGUAGE 'plpgsql' AS '
/*
|| Author: Tony Wasson
||
|| Overview: Experiment with arrays and aggregates
|| 3,2,1
|| + 0,2,2
|| -------
|| 3,4,3
||
|| Revisions: (when, who, what)
|| 2005/04/21 -- TW - Create function
*/
DECLARE inta1 ALIAS FOR $1; inta2 ALIAS FOR $2; out_arr INTEGER[]; out_arr_text TEXT := ''''; i
INTEGER; nextnum INTEGER;
BEGIN FOR i IN array_lower(inta1, 1)..array_upper(inta1, 1) LOOP RAISE NOTICE ''looking at element %'',i;
nextnum := COALESCE(inta1[i],0) + COALESCE(inta2[i],0); RAISE NOTICE ''nextnum %'',nextnum; out_arr_text
:=out_arr_text || nextnum::TEXT || '',''; RAISE NOTICE ''text %'',out_arr_text; END LOOP; RAISE NOTICE ''text
%'',out_arr_text; --drop the last comma IF SUBSTRING(out_arr_text,length(out_arr_text),1) = '','' THEN
out_arr_text:= substring(out_arr_text,1,length(out_arr_text)-1); END IF; out_arr_text := ''{'' || out_arr_text ||
''}''; RAISE NOTICE ''text %'',out_arr_text; out_arr := out_arr_text; RAISE NOTICE ''out_arr %'',out_arr;
RETURN out_arr;
END
';
SELECT sum_intarray('{1,2}','{2,3}');
SELECT sum_intarray('{3,2,1}','{0,2,2}');
--- Now I make a table to demonstrate an aggregate on
CREATE TABLE arraytest ( id character varying(10) NOT NULL, somearr integer[]
);
INSERT INTO arraytest (id, somearr) VALUES ('a', '{1,2,3}');
INSERT INTO arraytest (id, somearr) VALUES ('b', '{0,1,2}');
CREATE AGGREGATE sum_integer_array ( sfunc = sum_intarray, basetype = INTEGER[], stype = INTEGER[], initcond =
'{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}'
);
----------------------
# SELECT sum_integer_array(somearr) FROM arraytest; sum_integer_array
---------------------------------------------------------------------------------{1,3,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
Thanks in advance to anyone who reads this far.
Tony Wasson
ajwasson@gmail.com
You would definitely want to look into using pl/R for this. Also, other
procedure languages (perl, for example) work well with arrays so may be
easier to use for this situation. As for the aggregate, I don't know how to
make that more dynamic in terms of return value.
Sean
----- Original Message -----
From: "Tony Wasson" <ajwasson@gmail.com>
To: <pgsql-sql@postgresql.org>
Sent: Thursday, April 21, 2005 9:21 PM
Subject: [SQL] Looking for a way to sum integer arrays....
I'd like to be able to sum up an integer array. Like so:
{3,2,1} + {0,2,2} ------- {3,4,3}
The following solution I've been hacking on works, although I think it
is far from "ideal". Is there a built in way to sum up arrays? If not,
is there a better way than my crude method? I have tested this on 7.4
and 8.0. I'd also be appreciate if any insight on why my aggregate
fails to work when I have an empty initcondition. P.S. I have never
written an aggregate and I was lost trying to follow the complex_sum
example in the docs.
---------------------------------------------
CREATE OR REPLACE FUNCTION sum_intarray(INTEGER[],INTEGER[]) RETURNS
INTEGER[] LANGUAGE 'plpgsql' AS '
/*
|| Author: Tony Wasson
||
|| Overview: Experiment with arrays and aggregates
|| 3,2,1
|| + 0,2,2
|| -------
|| 3,4,3
||
|| Revisions: (when, who, what)
|| 2005/04/21 -- TW - Create function
*/
DECLARE inta1 ALIAS FOR $1; inta2 ALIAS FOR $2; out_arr INTEGER[]; out_arr_text TEXT := ''''; i
INTEGER; nextnum INTEGER;
BEGIN FOR i IN array_lower(inta1, 1)..array_upper(inta1, 1) LOOP RAISE NOTICE ''looking at element %'',i;
nextnum := COALESCE(inta1[i],0) + COALESCE(inta2[i],0); RAISE NOTICE ''nextnum %'',nextnum; out_arr_text
:=out_arr_text || nextnum::TEXT || '',''; RAISE NOTICE ''text %'',out_arr_text; END LOOP; RAISE NOTICE ''text
%'',out_arr_text; --drop the last comma IF SUBSTRING(out_arr_text,length(out_arr_text),1) = '','' THEN
out_arr_text:= substring(out_arr_text,1,length(out_arr_text)-1); END IF; out_arr_text := ''{'' || out_arr_text ||
''}''; RAISE NOTICE ''text %'',out_arr_text; out_arr := out_arr_text; RAISE NOTICE ''out_arr %'',out_arr;
RETURN out_arr;
END
';
SELECT sum_intarray('{1,2}','{2,3}');
SELECT sum_intarray('{3,2,1}','{0,2,2}');
--- Now I make a table to demonstrate an aggregate on
CREATE TABLE arraytest ( id character varying(10) NOT NULL, somearr integer[]
);
INSERT INTO arraytest (id, somearr) VALUES ('a', '{1,2,3}');
INSERT INTO arraytest (id, somearr) VALUES ('b', '{0,1,2}');
CREATE AGGREGATE sum_integer_array ( sfunc = sum_intarray, basetype = INTEGER[], stype = INTEGER[], initcond =
'{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}'
);
----------------------
# SELECT sum_integer_array(somearr) FROM arraytest; sum_integer_array
---------------------------------------------------------------------------------{1,3,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}Thanks
inadvance to anyone who reads this far.Tony Wassonajwasson@gmail.com---------------------------(end of
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cleanly
Thank you for the responses!
To recap: pl/r array support works very well. In my case, I am looking
for pl/pgsql solution.
I also got this nice function from dennisb on the #postgresql irc
channel, which seems extremely "clean" and works with 7.4/8.0. My
original function didn't handle a blank initcond in the aggregate
gracefully.
CREATE OR REPLACE FUNCTION array_add(int[],int[]) RETURNS int[] AS ' DECLARE x ALIAS FOR $1; y ALIAS FOR $2; a
int; b int; i int; res int[]; BEGIN res = x;
a := array_lower (y, 1); b := array_upper (y, 1);
IF a IS NOT NULL THEN FOR i IN a .. b LOOP res[i] := coalesce(res[i],0) + y[i]; END LOOP; END IF;
RETURN res; END;
'
LANGUAGE plpgsql STRICT IMMUTABLE;
--- then this aggregate lets me sum integer arrays...
CREATE AGGREGATE sum_integer_array ( sfunc = array_add, basetype = INTEGER[], stype = INTEGER[], initcond =
'{}'
);
Here's how my sample table looked and my new array summing aggregate
and function:
#SELECT * FROM arraytest ;id | somearr
----+---------a | {1,2,3}b | {0,1,2}
(2 rows)
#SELECT sum_integer_array(somearr) FROM arraytest ;sum_integer_array
-------------------{1,3,5}
(1 row)
Tony Wasson
Hi,
CREATE OR REPLACE FUNCTION SUM_ARR( aArr1 Integer[] , aArr2 Integer[] )
RETURNS Integer[] AS $$
DECLARE aRetu Integer[];
BEGIN
-- Initialize the Return array with first array value.
FOR i IN array_lower( aArr1 )..array_upper( aArr1 ) LOOP array_append( aRetu , aArr1[i] ); END LOOP;
-- Add the second array value to return array
FOR i IN array_lower( aArr2 )..array_upper( aArr2 ) LOOP if i > array_upper( aRetu ) then array_append( aRetu ,
aArr2[i]); else aRetu[i] = aRetu[i]+aArr2[i]; end; END LOOP;
RETURN aRetu;
END
$$ LANGUAGE 'plpgsql'
Regards,
R.Muralidharan
-----Original Message-----
From: Tony Wasson [mailto:ajwasson@gmail.com]
Sent: Friday, April 22, 2005 6:51 AM
To: pgsql-sql@postgresql.org
Subject: [SQL] Looking for a way to sum integer arrays....
I'd like to be able to sum up an integer array. Like so:
{3,2,1} + {0,2,2} ------- {3,4,3}
The following solution I've been hacking on works, although I think it
is far from "ideal". Is there a built in way to sum up arrays? If not,
is there a better way than my crude method? I have tested this on 7.4
and 8.0. I'd also be appreciate if any insight on why my aggregate
fails to work when I have an empty initcondition. P.S. I have never
written an aggregate and I was lost trying to follow the complex_sum
example in the docs.
---------------------------------------------
CREATE OR REPLACE FUNCTION sum_intarray(INTEGER[],INTEGER[]) RETURNS
INTEGER[] LANGUAGE 'plpgsql' AS '
/*
|| Author: Tony Wasson
||
|| Overview: Experiment with arrays and aggregates
|| 3,2,1
|| + 0,2,2
|| -------
|| 3,4,3
||
|| Revisions: (when, who, what)
|| 2005/04/21 -- TW - Create function
*/
DECLARE inta1 ALIAS FOR $1; inta2 ALIAS FOR $2; out_arr INTEGER[]; out_arr_text TEXT := ''''; i
INTEGER; nextnum INTEGER;
BEGIN FOR i IN array_lower(inta1, 1)..array_upper(inta1, 1) LOOP RAISE NOTICE ''looking at element %'',i;
nextnum := COALESCE(inta1[i],0) + COALESCE(inta2[i],0); RAISE NOTICE ''nextnum %'',nextnum; out_arr_text
:=out_arr_text || nextnum::TEXT || '',''; RAISE NOTICE ''text %'',out_arr_text; END LOOP; RAISE NOTICE ''text
%'',out_arr_text; --drop the last comma IF SUBSTRING(out_arr_text,length(out_arr_text),1) = '','' THEN
out_arr_text:= substring(out_arr_text,1,length(out_arr_text)-1); END IF; out_arr_text := ''{'' || out_arr_text ||
''}''; RAISE NOTICE ''text %'',out_arr_text; out_arr := out_arr_text; RAISE NOTICE ''out_arr %'',out_arr;
RETURN out_arr;
END
';
SELECT sum_intarray('{1,2}','{2,3}');
SELECT sum_intarray('{3,2,1}','{0,2,2}');
--- Now I make a table to demonstrate an aggregate on
CREATE TABLE arraytest ( id character varying(10) NOT NULL, somearr integer[]
);
INSERT INTO arraytest (id, somearr) VALUES ('a', '{1,2,3}');
INSERT INTO arraytest (id, somearr) VALUES ('b', '{0,1,2}');
CREATE AGGREGATE sum_integer_array ( sfunc = sum_intarray, basetype = INTEGER[], stype = INTEGER[], initcond =
'{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}'
);
----------------------
# SELECT sum_integer_array(somearr) FROM arraytest; sum_integer_array
---------------------------------------------------------------------------------{1,3,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
Thanks in advance to anyone who reads this far.
Tony Wasson
ajwasson@gmail.com
---------------------------(end of broadcast)---------------------------
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