Date:         Thu, 21 Jan 2010 21:14:47 -0600
Reply-To:     Yu Zhang <zhangyu05@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Yu Zhang <zhangyu05@GMAIL.COM>
Subject:      Re: Find the position of max/min value in an unsorted array
Comments: To: oloolo <dynamicpanel@yahoo.com>
In-Reply-To:  <201001220205.o0LKwXB6027680@malibu.cc.uga.edu>
Content-Type: text/plain; charset=ISO-8859-1

WhichN function will give you the position of that matching maximum value.
if you have more than 1 maximum value, the position return is the first one.

data _null_;
       array _A{*}  X1-X10;
 do j=1 to 10;
_A[j]=ranuni(999);
put _A[j]=;
end;
 maxv=max(of _A[*]);
Index=whichN(maxv,of _A[*]);
put (maxv index)(=/);
run;

HTH

Yu


On Thu, Jan 21, 2010 at 8:05 PM, oloolo <dynamicpanel@yahoo.com> wrote:

> Just come across this in my mind. MAX/MIN function in SAS is able to find
> the Max or Min value of a given array. If we want to position this max /min
> value in the array, we probablly have to do something like this:
>
> data _null_;
>        array _A{*}  X1-X10;
>  do j=1 to 10; _A[j]=ranuni(999); end;
>  maxv=max(of _A[*]);
>  notfound=1;
>  do j=1 to dim(_A) & notfound;
>            notfound=(maxv=_A[j]);
>        end;
>  put j=;
> run;
>
> this is inefficient when encounter a very large unsorted matrix _A[*] and
> the worst case need dim(_A) operations.
>
> any more elegent solutions in SAS?
>