Date:         Thu, 18 Nov 2004 04:44:35 -0800
Reply-To:     Dennis Diskin <diskin@SNET.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Dennis Diskin <diskin@SNET.NET>
Subject:      Re: FIRST. / LAST. Processing with Arrays
Comments: To: m n <iced_phoenix_news@YAHOO.COM>
In-Reply-To:  <20041117225250.43308.qmail@web52805.mail.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Matt,

One way would be to build a temporary array holding to hold the values fof first.key[i] and populate it vis a macro loop. Not very efficient if you are deling with large files.

example:

%macro first(N=N,first=first,key=key);
%local i;
array &first(&N) _temporary_;
%do i = 1 %to &N;
  &first.&i = first.&key.&i;
%end;
%mend first;

data blah;
set mydata;
by key1-key&N;
%first;

/* then use the first array as you would have used first.key[n] */

do i = 1 to &n;
  if first(i) then
     do whatever;
      end;
end;

HTH,
Dennis Diskin


m n <iced_phoenix_news@YAHOO.COM> wrote:
SAS-L,

Consider the following code (assume mydata is properly
sorted on by-variables, N is defined, etc):

data blah;
set mydata;
by key1-key&N;

array key[&N];

do I=1 to &N;
if first.key[I] then do; /* something */ end;
end;
run;

Clearly, the "first.key[I]" is not syntactically valid
in SAS, but is it possible to achieve the intended
effect without resorting to a macro array/loop such
as:

%do I=1 %to &N;
if first.key&I then do; /* something */ end;
%end;

Thanks for your help!
Matt



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