Date:         Tue, 8 Oct 1996 18:00:42 +0100
Reply-To:     Hans-Peter Piepho <piepho@WIZ.UNI-KASSEL.DE>
Sender:       "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From:         Hans-Peter Piepho <piepho@WIZ.UNI-KASSEL.DE>
Subject:      Re: A SUBSET QUESTION
Comments: To: ANDY_YUAN@SMTPLINK.MSSM.EDU

>     Hi, friends, I need help for a data subsetting task:
>
>     data: similar to the sample below
>
>     want: for every id, capture every unit change. (e.g. for id=1, keep
>     date=960101, 960104; for id=2 keep date=960212, 960214, 960216...)
>
>
>     ID   DATE   UNIT
>     ...  ...    ...
>     1    960101  A
>     1    960102  A
>     1    960103  A
>     1    960104  B
>     1    960105  B
>     1    960106  B
>     2    960212  A
>     2    960213  A
>     2    960214  B
>     2    960215  B
>     2    960216  A
>     2    960217  A
>     3    960123  C
>     3    960124  C
>     3    960125  C
>     3    960126  C
>     4    960303  B
>     4    960304  B
>     4    960305  A
>     4    960306  A
>     4    960307  C
>     4    960308  C
>     4    960309  C
>     5    960511  A
>     5    960512  B
>     5    960513  B
>     5    960514  A
>     5    960515  A
>     ...  ...     ...
>
>     Any suggestion will be appreciated.
>
>     Andy
>
>
 
Try this:
 
DATA temp;
  INPUT  id date unit $;
CARDS;
     1    960101  A
     1    960102  A
     1    960103  A
     1    960104  B
     1    960105  B
     1    960106  B
     2    960212  A
     2    960213  A
     2    960214  B
     2    960215  B
     2    960216  A
     2    960217  A
     3    960123  C
     3    960124  C
     3    960125  C
     3    960126  C
     4    960303  B
     4    960304  B
     4    960305  A
     4    960306  A
     4    960307  C
     4    960308  C
     4    960309  C
     5    960511  A
     5    960512  B
     5    960513  B
     5    960514  A
     5    960515  A
;
DATA result;
DO i=1 TO last-1;
  SET temp POINT=i;
  unit_pre=unit;
  IF i=1 THEN OUTPUT;
  next=i+1;
  SET temp POINT=next NOBS=last;
  unit_nex=unit;
  IF unit_nex^=unit_pre THEN output;
END;
STOP;
 
PROC PRINT DATA=result;
RUN;
 
             OBS    ID     DATE     UNIT    UNIT_PRE    UNIT_NEX
 
               1     1    960101     A         A
               2     1    960104     B         A           B
               3     2    960212     A         B           A
               4     2    960214     B         A           B
               5     2    960216     A         B           A
               6     3    960123     C         A           C
               7     4    960303     B         C           B
               8     4    960305     A         B           A
               9     4    960307     C         A           C
              10     5    960511     A         C           A
              11     5    960512     B         A           B
              12     5    960514     A         B           A
 
Hans-Peter
_______________________________________________________________________
Hans-Peter Piepho
Institut f. Nutzpflanzenkunde  WWW:   http://www.wiz.uni-kassel.de/fts/
Universitaet Kassel            Mail:  piepho@wiz.uni-kassel.de
Steinstrasse 19                Fax:   +49 5542 98 1230
37213 Witzenhausen, Germany    Phone: +49 5542 98 1248