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Hi,
set test nobs = nobs point = nobs;
is just so neat. Excellent!
++ Guido
On 09/08/06, Venky Chakravarthy <swovcc@hotmail.com> wrote:
> Rob Workman has kindly pointed out that the first SET statement is
> unnecessary.
>
> Thanks for the tip. This is really neat.
>
> Venky
>
> ----Original Message Follows----
> From: "Workman, Rob" <Rob.Workman@sorin-na.com>
> To: "Venky Chakravarthy" <swovcc@HOTMAIL.COM>
> Subject: RE: Re: how to pick out the last observation of a data set?
> Date: Wed, 9 Aug 2006 08:47:20 -0500
>
> Venky,
>
> Your technique works, but the extra set statement is not necessary.
> Since variables created using set statement options are initialized at
> compile time, you can just use:
>
>
> data lastobs;
> set test nobs = nobs point = nobs;
> output;
> stop;
> run;
>
>
> Rob
>
>
>
> Rob Workman
> Sorin-na
>
> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
> Venky Chakravarthy
> Sent: Wednesday, August 09, 2006 8:32 AM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: how to pick out the last observation of a data set?
>
> On Wed, 9 Aug 2006 04:55:42 -0400, Wu Shengzhe <sas.shengzhe@GMAIL.COM>
> wrote:
>
> >Hello,
> >
> >When a data set has been read into SAS, how to pick out the last
> >observation of this data set?
> >
> >Thank you,
> >Shengzhe
>
> If you want only the last observation then you may choose to have random
> access to it.
>
> data test ;
> do x = 1 to 10 ;
> output ;
> end ;
> run ;
>
> data lastobs ;
> if 0 then set test nobs = nobs ;
> set test point = nobs ;
> output ;
> stop ;
> run ;
>
> This will read just the last observation and output it. The first SET,
> which is always false loads the header information that has the number
> of
> observations in it. The last observation is NOBS. The second SET
> statement
> is instructed to directly fetch only this observatiopn. Since we break
> the
> rules of the default data step behavior, we also need to instruct the
> data
> step to stop processing soon after outputting this observation.
>
> Some may point out that if the data set is modified in place then this
> logic could fail. Very true. However, in practice, at least in the field
> that I work, I have seen datasets modified in place very rarely.
>
> Venky Chakravarthy
>
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