Date:         Sun, 21 May 2006 22:53:01 -0700
Reply-To:     David L Cassell <davidlcassell@MSN.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         David L Cassell <davidlcassell@MSN.COM>
Subject:      Re: Creating combinations in SAS
In-Reply-To:  <200605211258.k4LAlaVZ004671@mailgw.cc.uga.edu>
Content-Type: text/plain; format=flowed

rdevenezia@WILDBLUE.NET replied:
>saurabh wrote:
> > Hi All ,
> >
> > I am new to SAS, however I am asked to do some work beyond that
> > knowledge level and its going over my head and understanding .  ok
> > lets get to it ....
> >
> > Ok the present method what I am doing is ....
> >
> > I have a set of 20 variables. I need combinations of 4 each.
> > 1. creating a combination of those 20 variables.  this should come out
> > into a data set.
>
>Perhaps in future releases of SAS there will be an ALLCOMB function.

I have heard rumors that such a function may appear one of these days.

>In the meantime, a simple m-m-m-m-macro can enumerate all the combinations
>by generating a DATA Step source code that contains the requisite number of
>nested and properly bounded loops.
>
>%macro allcomb (n=6,k=3);
>   data combos_&n._&k.;
>     i0=0;
>     %do i = 1 %to &k;
>       do i&i = i%eval(&i-1)+1 to %eval(&n-&k+&i);
>     %end;
>       output;
>       n+1;
>     %do i = 1 %to &k;
>       end;
>     %end;
>     drop i0;
>   run;
>%mend;
>
>options mprint;
>
>%allcomb(n=20,k=4);

But this is not needed for PROC REG.  Just look at the SELECTION=
options.

Or don't.  Let's pretend there is no such option.  It was all a bad
dream.  :-)  :-)

> > 2. running proc reg on the combinations , by picking up each variable
> > to be a dependant variable and running proc reg on those 4895
> > combinations . With all values of Proc Reg coming out ( ie R Sqaure
> > and Adj R Square  and the test of significance ) into a dataset.
>
>Someone, somewhere in the world has blanched and is turning an awful shade
>a
>green.

That would be me.

David
--
David L. Cassell
mathematical statistician
Design Pathways
3115 NW Norwood Pl.
Corvallis OR 97330

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