Re: MAX of _TEMPORARY_ array?

See below.

On Fri, 24 Jun 2005 23:39:22 -0400, Talbot Michael Katz <topkatz@MSN.COM>
wrote:

>Hi, Roy.
>
>When using a _temporary_ array it appears that there is NO access to the
>var list, only to the array elements. Unfortunately, although you can use
>
>max(of v1 - v&n.)
>
>
>you can't use
>
>max(of b{1} - b{&n.})
>
>
>And it looks like you can use
>
>max(of c{*})
>
>
>only when c{} is declared like
>
>array c{*} var1 - var&n.;
>
>
>and not if you declare
>
>array c{&n.} var1 - var&n.;
>
>
>But for a _temporary_ array, you have to declare the size
>
>array t{&n.} _temporary_;
>
>
>In my case, I can certainly find the maximum of the array by keeping track
>of the largest element as the array gets initialized, as Kevin Viel
>suggested, but what happens after that is that one element of the array
>gets modified with each data step iteration. That might change the
>maximum. So it seems that, to get the new maximum, I'll either have to
>loop through the entire array, or use a macro, as John McQuown suggested,
>to generate a list of all the array variables inside the max function. I
>suppose another alternative would be to try to keep an ordered version of
>the array, but that would need to be re-ordered each time an element
>changed, so it's roughly equivalent to looping through the array.

It seems to me that you can still keep track of the maximum on a running
basis. Here is a demo, with the array being loaded on the first pass, then
one element getting changed on each subsequent pass:

data _null_;
set sashelp.class;
array ta(19) _temporary_;

if _n_=1 then do i = 1 to 19;
ta(i) = floor(ranuni(1)*10);
link runningmax;
end;

i = _n_;
ta(i) = age;
link runningmax;

return;

runningmax:
retain high;
high = max(high,ta(i) );
put _n_= high=;
return;

run;

>
>
>-- TMK --
>"The Macro Klutz"
>
>On Fri, 24 Jun 2005 14:28:46 -0700, Pardee, Roy <pardee.r@GHC.ORG> wrote:
>
>>I guess what I don't understand is how you have a var list to actually
>>*populate* the temp array, but you don't have it when time comes to find
>>the max value. If your goal is simply to find the max value (and no
>>doubt it isn't) you don't need an array at all.
>>
>>-----Original Message-----
>>From: Talbot Michael Katz [mailto:topkatz@MSN.COM]
>>Sent: Friday, June 24, 2005 2:20 PM
>>To: SAS-L@LISTSERV.UGA.EDU; Pardee, Roy
>>Cc: Talbot Michael Katz
>>Subject: Re: MAX of _TEMPORARY_ array?
>>
>>
>>Hi, Roy.
>>
>>Thank you for responding. Yes,
>>
>>maxa = max(of a1 - a&dima.) ;
>>
>>works fine for a regular array declared as
>>
>>array a{*} a1 - a&dima. ;
>>
>>but what if the array is declared as a _temporary_ array, i.e.,
>>
>>array a{&dima.} _temporary_ ;
>>
>>Then the variable names in the array, a{}, are not a1 - a&dima.; you
>>can't specify them a priori. I think you could retrieve them with CALL
>>VNAME, but I'm not sure how that would help. Meanwhile, I haven't found
>>a way of using the max function for a _temporary_ array without looping
>>through the array (which is what I wanted to avoid, if possible).
>>
>>-- TMK --
>>"The Macro Klutz"