Date:         Fri, 24 Sep 2010 13:38:24 -0400
Reply-To:     sas quest <sasquest@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         sas quest <sasquest@GMAIL.COM>
Subject:      Re: Using retain
In-Reply-To:  <AANLkTikfNveZC3KSN_qcMcez4=y7fk5JfVSaCWUyZKac@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hello Ian,
Your solution doesn't address my problem.
For example  consider 'types' as trials.trial B is an extension of trial A
and trial C is an extension of trial B and so on.Here,after a sub reaches
trial B his values(ex:days) need to be added from the last value in trial A
which becomes the baseline.Thanks for adding a couple of rows with type=C
which further complicates the problem.

When i ran your code the result,sixth row of n_val shows 47 which in
fact should be 46(41+5) since the baseline is 41 which is the last value of
type A for sub=1.

Thanks

On Fri, Sep 24, 2010 at 12:56 PM, Ian Whitlock <iw1sas@gmail.com> wrote:

> Summary: Example data has to be general enough to show the problem.
>         If you want to do something with the last value of type,
>         then you have to know the value of last type.
> #iw-value=1
>
> SAS Quest,
>
> Part of the problem is not giving a sufficiently general example.
> Suppose the data looks like:
>
> data have;
> input sub type$ val;
> cards;
> 1       A       20
> 1       A       30
> 1       A       36
> 1       A       41
> 1       B        1
> 1       B        5
> 1       B       11
> 1       B       19
> 2       A       12
> 2       A       20
> 2       A       29
> 2       A       31
> 2       B        3
> 2       B       10
> 2       B       11
> 2       C        7
> 2       C       30
> run;
>
> What do you want as a result?  It could be that this is too general.
> Perhaps all SUBS have precisely the same TYPES.  Simplifying Art's
> code and complicating it with getting information ahead of time.
> There are are two possibilities depending on what you want.
>
> 1) Same types in all SUBs.
>
> data _null_ ;
>   set have ;
>   by sub ;
>   if last.sub ;
>   call symput ( "lasttype" , type ) ;
>   stop;
> run ;
>
> data want;
>  set have;
>   if type ^= &lasttype then do;
>     val_=val;
>    n_val=val;
>  end;
>   else n_val+val;
> run;
>
> 2) Any SUB can have any TYPEs.
>
> data cntl ( keep = sub lasttype ) ;
>   set have ;
>   by sub ;
>   if last.sub ;
>   lasttype = type ;
> run ;
>
> data want;
>  merge have cntl ;
>  by sub ;
>   if type ^= lasttype then do;
>     val_=val;
>    n_val=val;
>  end;
>   else n_val+val;
> run;
>
> Note the second version works with either interpretation, but
> the first is more efficient when it is appropriate, becasue
> there is less IO done.
>
> Ian Whitlock
> ===============
>
> Date:         Fri, 24 Sep 2010 10:36:59 -0400
> From:         Sas Quest <sasquest@GMAIL.COM>
> Subject:      Using retain
>
> data have;
> input sub type$ val;
> cards;
> 1       A       20
> 1       A       30
> 1       A       36
> 1       A       41
> 1       B        1
> 1       B        5
> 1       B       11
> 1       B       19
> 2       A       12
> 2       A       20
> 2       A       29
> 2       A       31
> 2       B        3
> 2       B       10
> 2       B       11
> run;
>
>
> Want:
> Sub    type     val  n_val
> 1       A       20   20
> 1       A       30   30
> 1       A       36   36
> 1       A       41   41
> 1       B        1   42
> 1       B        5   46
> 1       B       11   52
> 1       B       19   60
> 2       A       12   12
> 2       A       20   20
> 2       A       29   29
> 2       A       31   31
> 2       B        3   34
> 2       B       10   41
> 2       B       11   42
>
>
> my code:
>
>
> data want;
> set have;
> by sub type;
> retain val_ 0;
> n_val=val_+val;
> /*f=first.type;
> l=last.type;*/
> if last.type then val_=val;
> drop val_;
> run;
>
>
>
>
> What can be modified in my code to get the desired output?
>
>
> Thanks
>