Re: Multi-dimensional Array

From: M <someone_at_microsoft.com>
Date: Sun, 23 Mar 2003 17:00:50 +0800
Message-ID: <b5jtqt$30hd$1@news.hgc.com.hk>

Thanks. But I do have a problem in using this because: (1) I need to have a multi-dimensional array up to 12 parameters; and (2) It's not easy to proof that the mapping function is 1-to-1.

Thanks.

"Ed Prochak" <edprochak_at_adelphia.net> wrote in message news:3E7B6418.9060100_at_adelphia.net...
> M wrote:
> > pl/sql table is only single-dimension. for example,
> >
> > declare
> > type score_type is table of number(3) index by binary_integer;
> > my_score score_type;
> > begin
> > for a in 1 .. 100 loop
> > my_score(a) := a;
> > end loop;
> > end;
> >
> > Then I can assign values to my_score(a), a single-dimension array. Just
> > want to know if there is something like, e.g. 2-dimensional arrays like
> > my_score(a, b) ... or even multi-dimensional.
> >
> > M.
> >
> > "Jim Kennedy" <kennedy-downwithspammersfamily_at_attbi.com> wrote in
message
> > news:U1lda.141918$S_4.82850_at_rwcrnsc53...
> >
> >>How about using pl/sql tables?
> >>Jim
> >>"M" <someone_at_microsoft.com> wrote in message
> >>news:b53ej3$2144$1_at_news.hgc.com.hk...
> >>
> >>>Hi all,
> >>>
> >>>Just want to know in Oracle 8i, can I define some multi-dimensional
> >>
> > array
> >
> >>to
> >>
> >>>store data for analysis purpose. Can this kind of array be define on
> >>
> > the
> >
> >>>fly, instead of some objects in the database?
> >>>
> >>>Thx.
> >>>M.
> >>>
> >>>
> >>
> >>
> >>
> >
> >

>
>

> A google search for "two dimensional array" brings up an article I've
posted
> before. But here we go again, you can simulate a two dimensional array
with a
> simple mapping function. It's usually what your compiler does when you use
a
> multidimensional array in languages that support it. So no need for nested
> types and tables.

>


>   ----- INDEX2D

>   ----- GIVEN THE INDICES IN A 2-DIMENSIONAL ARRAY.

>   ----- THIS RETURNS A UNIQUE INDEX IN A LINEAR ARRAY.

>   -----

>   ----- Ed Prochak

>   ----- Magic Interface, Ltd.

> ----- 440-498-3702
> -----
> CREATE OR REPLACE FUNCTION INDEX2D ( A INTEGER, B INTEGER )
> RETURN INTEGER
> AS
> K INTEGER;
> N INTEGER;
> NDX INTEGER;
> BEGIN
> K := A+B-1;
> N := K*(K+1);
> N := N/2;
> NDX := N+1-B;
> RETURN NDX;
> END;
> /

>

> The above routine assumes the first entry in the table is
> location (1,1) in the 2-D array and location 1 in the linear array.
> It also assumes use of only positive integers. If you prefer
> your 2-D array to start at location (0,0), then simply add 1
> to both parameters before calling this routine OR adjust the body
> as follows:
> BEGIN
> K := A+B+1;
> N := K*(K+1);
> N := N/2;
> NDX := N-B;
> RETURN NDX;
> END;

>

> Feature: This is an unlimited 2-D array, well suited for use
> with PL/SQL tables. So don't forget to check that the entry
> exists at a given location before retrieving it.

>

> So you use this within you PL/SQL code for example:

>


> DECLARE

>     TYPE EJP_TABLE IS TABLE OF VARCHAR2(30)

>                INDEX BY BINARY_INTEGER;

>     LYNEAR  EJP_TABLE;

> BEGIN

>     LYNEAR(2):='TWO';  --- IT REALLY IS A LINEAR ARRAY

>     LYNEAR(INDEX2D(1,2)):='xxx';  --- but INDEX2D allows you to pretend

it's 2D


>     LYNEAR(INDEX2D(2,2)):='YYY';

>     LYNEAR(INDEX2D(3,5)):='ZZZ';  --- GREAT FOR SPARSE MATRICES TOO.

>


>     DBMS_OUTPUT.PUT_LINE('@(2) = '|| LYNEAR(2) );

>     DBMS_OUTPUT.PUT_LINE('@(1,2)) = '||LYNEAR(INDEX2D(1,2))||

>                    ' @'||INDEX2D(1,2) );

>     DBMS_OUTPUT.PUT_LINE('@(2,2)) = '||LYNEAR(INDEX2D(2,2))||

>                    ' @'||INDEX2D(2,2) );

>     DBMS_OUTPUT.PUT_LINE('@(3,5)) = '||LYNEAR(INDEX2D(3,5))||

>                    ' @'||INDEX2D(3,5) );

> END;
> /

>

> There is an obvious limit on using this function, ie
> you have to use it whenever you use the array.

>

> Not a built in feature of PL/SQL, but very flexible none-the-less.

>
>

> It can be extended to multiple demensions. You just need to do the math.

>

> HTH
> Ed

>
>

> --
> Ed Prochak
> running: http://www.faqs.org/faqs/running-faq/
> family: http://web.magicinterface.com/~collins
> --
> "Two roads diverged in a wood and I
> I took the one less travelled by
> and that has made all the difference."
> robert frost

> Received on Sun Mar 23 2003 - 03:00:50 CST