Date:         Wed, 2 Apr 2003 13:03:59 +0800
Reply-To:     Zibao Zhang <zibaozhang@HOTMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Zibao Zhang <zibaozhang@HOTMAIL.COM>
Subject:      Re: How add a new variable to flag the visit time according to
              valuesof another variables?
Comments: To: Paul Homes <pahomes@ZZZtekeds.com>
Content-Type: text/plain; charset="iso-8859-1"

Paul, thank you very much! You code works well.

Kind Regards,
Zibao Zhang, MD


----- Original Message -----
From: Paul Homes <pahomes@ZZZtekeds.com>
To: Zibao Zhang <zibaozhang@HOTMAIL.COM>
Cc: <SAS-L@LISTSERV.UGA.EDU>
Sent: Tuesday, April 01, 2003 3:13 PM
Subject: Re: How add a new variable to flag the visit time according to valuesof another variables?


> Zibao Zhang wrote:
> > Hi SAS-Ler,
> >
> > I have a dataset like this,
> >
> > Subj_No  Vist_date    A     B
> >
> > 1001     01/01/2000   xx    xx
> > 1001     02/01/2000   xx    xx
> > 1002     01/03/2000   xx    xx
> > 1002     02/04/2000   xx    xx
> > 1002     03/16/2000   xx    xx
> > 1003     01/11/2000   xx    xx
> > 1004     01/15/2000   xx    xx
> > 1004     03/10/2000   xx    xx
> > ....
> >
> > I want to add a new variable(vist_id) to flag the visit time, like:
> >
> > Subj_No  Vist_date    A     B    Vist_id
> >
> > 1001     01/01/2000   xx    xx    01
> > 1001     02/01/2000   xx    xx    02
> > 1002     01/03/2000   xx    xx    01
> > 1002     02/04/2000   xx    xx    02
> > 1002     03/16/2000   xx    xx    03
> > 1003     01/11/2000   xx    xx    01
> > 1004     01/15/2000   xx    xx    01
> > 1004     03/10/2000   xx    xx    02
> > ...
> >
> > It seems that I can use "by subj_no vist_date" in datastep. I can only get the first and last using the automatic variables of "first." and "last.", but subjects were visited by many times, which was not fixed. How to add the flag variable??
> >
> > Thanks in advance.
> >
> > Kind Regards,
> > Zibao Zhang, MD
> >
>
> Hi Zibao,
>
> The technique is to accumulate a visit counter and use a first. flag to
> reset it when a new subject is encountered.  Try something like.
>
> data work.test;
> infile cards firstobs=2;
> input Subj_No Vist_date:mmddyy10. a $ b $;
> format Vist_date mmddyy10.;
> cards;
> Subj_No  Vist_date    A     B
> 1001     01/01/2000   xx    xx
> 1001     02/01/2000   xx    xx
> 1002     01/03/2000   xx    xx
> 1002     02/04/2000   xx    xx
> 1002     03/16/2000   xx    xx
> 1003     01/11/2000   xx    xx
> 1004     01/15/2000   xx    xx
> 1004     03/10/2000   xx    xx
> ;
> run;
>
> proc sort data=work.test;
> by Subj_No Vist_Date;
> run;
>
> data work.test;
> set work.test;
> by Subj_No;
> if first.Subj_No then Vist_id=0;
> Vist_id+1;
> format Vist_id z2.;
> run;
>
> Cheers
> Paul
> --
> Paul Homes ( email: pahomes@ZZZtekeds.com )
> TekEds.com Pty Ltd ( web: http://www.tekeds.com/ )
> --
> *** Remove ZZZ from email address to reply ***
>
>