Date:         Thu, 5 Nov 2009 10:51:38 -0500
Reply-To:     Jonathan Goldberg <jgoldberg@BIOMEDSYS.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Jonathan Goldberg <jgoldberg@BIOMEDSYS.COM>
Subject:      Re: how to establish variable with macro
Comments: To: Murphy Choy <goladin@GMAIL.COM>

Murphy:

The trouble with the macro solution you have been given is that it
clutters up the data set with variables that aren't being used.

This can be fixed by a macro-generated drop statement:
   drop
    %do i = 2 %to &nvars %by 2;
         x&i
     %end;
   ;   /*ends the drop statement*/

However, to answer the question as it was asked, the original solution
will work with one change: move the "output" statement need to be moved
inside the inner loop, so:

>> %macro a(x,y);
>> data b;
>> %do i=1 %to &x;
>> %do j=1 %to &y %by 2;
>> x&j=rannor(254115);
OUTPUT;  /*new location*/
>> %end;
>> output;  /*old location, delete this line*/
>> %end;
>> run;
>> %mend a;
>> %a(10,10);

Cheers,

Jonathan


On Thu, 5 Nov 2009 15:12:16 +0000, Murphy Choy <goladin@GMAIL.COM> wrote:

>Hi Nicky,
>
>This macro is more efficient than the one you have written. Please use
this one instead.
>
>
>------Original Message------
>From: Tom Abernathy
>Sender: SAS(r) Discussion
>To: SAS-L@LISTSERV.UGA.EDU
>ReplyTo: Tom Abernathy
>Subject: Re: how to establish variable with macro
>Sent: Nov 5, 2009 9:37 PM
>
>Don't use macro logic do what you can do with DATA step logic.
>Also use meaningful variable names. I renamed X and Y macro variables
>based on how they appear to be used.
>This makes it more obvious that half of your Xnn variables will never
>be assigned values because of the BY clause on the inner DO loop.
>
>%macro a(nobs,nvars);
>  data b;
>    array x x1-x&nvars;
>    do i=1 to &nobs;
>      do j=1 to &nvars by 2;
>        x(j)=rannor(254115);
>      end;
>      output;
>    end;
>  run;
>%mend a;
>%a(10,10);
>
>
>On Nov 5, 3:08 am, nickyli <nickyli0...@gmail.com> wrote:
>>
>> because of my poor english,someone maybe misunderstood the
>> meaning.however,i have solve the problem.here is the procedure:
>> %macro a(x,y);
>> data b;
>> %do i=1 %to &x;
>> %do j=1 %to &y %by 2;
>> x&j=rannor(254115);
>> %end;
>> output;
>> %end;
>> run;
>> %mend a;
>> %a(10,10);
>> we can get different data set by changing macroparameter (x,y)- Hide
quoted text -
>>
>> - Show quoted text -
>
>
>Sent from my BlackBerry Wireless Handheld
>
>--
>Regards,
>Murphy Choy
>
>Certified Advanced Programmer for SAS V9
>Certified Basic Programmer for SAS V9