Date:         Tue, 16 Mar 2010 18:32:43 -0400
Reply-To:     "Kirby, Ted" <ted.kirby@LEWIN.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Kirby, Ted" <ted.kirby@LEWIN.COM>
Subject:      Re: how to retain scores
Comments: To: sas analysis <sasanalysis@GMAIL.COM>
In-Reply-To:  A<990a7aef-d1a9-4413-ac6e-0bd1edfa36d0@p3g2000pra.googlegroups.com>
Content-Type: text/plain; charset="us-ascii"

Try this.  It is a bit verbose, but seems to work on your test data:

data have;
input id score;
datalines;
1 2.8
1 .
1 3.5
1 .
1 4.0
2 2.2
2 .
2 .
2 2.3
2 .
4 5.5
4 5.7
4 .
4 .
4 4.6
4 .
;
run;
proc print; run;

data want(drop=tscore oldscore);
set have;
retain oldscore;
if first.id then oldscore=score;
/*  Need to account for the possibility of consecutive missing values,
so
    will introduce a new variable tscore as a temporary variable.  */
else do;
        tscore=lag(score);
        if tscore ne . then oldscore=tscore;
end;
if score=. then score=oldscore;
run;
proc print; run;

-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of sas
analysis
Sent: Tuesday, March 16, 2010 5:10 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: how to retain scores

Hi All,

I have scores for each subject at various time points. In certain
visits, scores were missing but in others recorded.
How can I input scores where missing based on the previous score. and
when a new score is recorded it remains and the following that are
missing take its value. This is a large dataset with more than 10000
observations. I have tried retain with first.subject code.

This is how the data looks:

Subject        Score
1                    2.8
1                      .
1                    3.5
1                      .
1                    4.0
2                    2.2
2                      .
2                      .
2                    2.3
2                      .
4                    5.5
4                    5.7
4                     .
4                     .
4                   4.6
4                    .


This is how I want the data to look:
Subject        Score
1                    2.8
1                    2.8
1                    3.5
1                    3.5
1                    4.0
2                    2.2
2                    2.2
2                    2.2
2                    2.3
2                    2.3
4                    5.5
4                    5.7
4                    5.7
4                    5.7
4                    4.6
4                    4.6


This is what I am trying to code:
data x;
set y;
retain scores;
if first.scores then score2;
else score2=scores;
run;

any ideas would be great?
Thanks!
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