Date:         Fri, 8 May 2009 18:50:31 -0400
Reply-To:     Arthur Tabachneck <art297@NETSCAPE.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Arthur Tabachneck <art297@NETSCAPE.NET>
Subject:      Re: First and Last Observations.
Comments: To: SUBSCRIBE SAS-L Anonymous <randistan69@HOTMAIL.COM>

Randy,

Either your example isn't correct, or I misunderstood what you are trying
to accomplish.

I'd think something like the following does what you want:

data have;
  set have;
  rec_order=_n_;
run;

proc sort data=have;
  by id_a id_b;
run;

data want;
  set have;
  by id_a id_b;
  if first.id_b then Flag_FO=1;
   else Flag_FO=0;
  if last.id_b then Flag_LO=1;
   else Flag_LO=0;
run;

proc sort data=want;
  by rec_order;
run;

Art
-------
On Fri, 8 May 2009 17:20:29 -0400, Randy <randistan69@HOTMAIL.COM> wrote:

>Dear All:
>
>My data set is as follows (ID_A and ID_B as a unit should be considered as
>one ID):
>
>
>Date      Code     ID_A       ID_B      Time
>May1       1        AB1        MN        10:00
>May1       1        AB4        MN        10:00
>May1       1        AB2        MO        10:01
>May1       1        AB1        MN        10:05
>May1       1        AB1        MN        11:05
>May1       1        AB2        MO        11:15
>May1       1        AB4        MN        11:25
>May1       2        AB3        MO        10:03
>May1       2        AB1        MN        10:05
>May1       2        AB2        MA        10:06
>May1       2        AB3        MO        11:19
>May1       2        AB1        MN        12:20
>May1       2        AB2        MA        13:21
>May1       2        AB1        FG        13:25
>May2       1        AB1        MN        9:31
>May2       1        AB2        MO        9:45
>May2       1        AB1        MN        10:31
>May2       2        AB3        MO        11:45
>May2       2        AB1        MN        12:36
>May2       2        AB3        MO        12:45
>
>I want to construct a data set with two flags.  The first flag (flag = 1
if
>first observation, 0 otherwise) is the flag of the first observation of
ID_A
>and ID_B on a particular date and for a particular code.  The second flag
>(flag = 1 if last observation, 0 otherwise)is the flag of the last
>observation of ID_A and ID_ on a particular date and particular code. If
>there is only one observation then the flag for the first observation and
>the last observation will both equal 1.  So the output should look like
this:
>
>Date  Code  ID_A    ID_B     Time       Flag_FO     Flag_LO
>May1   1     AB1     MN      10:00          1        0
>May1   1     AB4     MN      10:00          1        0
>May1   1     AB2     MO      10:01          1        0
>May1   1     AB1     MN      10:05          0        0
>May1   1     AB1     MN      11:05          0        1
>May1   1     AB2     MO      11:15          0        1
>May1   1     AB4     MN      11:25          0        1
>May1   2     AB3     MO      10:03          1        0
>May1   2     AB1     MN      10:05          1        0
>May1   2     AB2     MA      10:06          1        0
>May1   2     AB3     MO      11:19          0        1
>May1   2     AB1     MN      12:20          0        1
>May1   2     AB2     MA      13:21          0        1
>May1   2     AB1     FG      13:25          1        1
>May2   1     AB1     MN      9:31           1        0
>May2   1     AB2     MO      9:45           1        1
>May2   1     AB1     MN      10:31          1        1
>May2   2     AB3     MO      11:45          1        0
>May2   2     AB1     MN      12:36          1        1
>May2   2     AB3     MO      12:45          0        1
>
>Thanx
>Randy