topic Re: How do I used a %do loop to make this code more efficient? in SAS Programming

How do I used a %do loop to make this code more efficient?

baroche64 — Sun, 20 Feb 2022 21:26:02 GMT

I'm trying to use a %do loop to replicate what the commented out code below does which is to simply set up some counters for 5 crops. The commented code works perfectly, but how do I achieve the same more efficiently using a %DO?
I tried using &TopCrop&i.._Farm but that doesn't work either, what am I doing wrong? Thanks for helping.

if Second_Level_Validation eq "Pass" or Main_Farm_Commodity in ("&TopCrop1.","&TopCrop2.","&TopCrop3.","&TopCrop4.","&TopCrop5.")  then 
	    do;
          %do i = 1 %to 5;
	      if Main_Farm_Commodity eq "&TopCrop&i." then &TopCrop&i._Farm = 1; 
              else &TopCrop&i._Farm = 0;
          %end;
		  /*
          if Main_Farm_Commodity eq "&TopCrop1." then &TopCrop1._Farm = 1; 
          else &TopCrop1._Farm = 0;
		  if Main_Farm_Commodity eq "&TopCrop2." then &TopCrop2._Farm = 1; 
          else &TopCrop2._Farm = 0;
		  if Main_Farm_Commodity eq "&TopCrop3." then &TopCrop3._Farm = 1; 
          else &TopCrop3._Farm = 0;
		  if Main_Farm_Commodity eq "&TopCrop4." then &TopCrop4._Farm = 1; 
          else &TopCrop4._Farm = 0;
		  if Main_Farm_Commodity eq "&TopCrop5." then &TopCrop5._Farm = 1; 
          else &TopCrop5._Farm = 0;
		*/
		end;

Re: How do I used a %do loop to make this code more efficient?

Kurt_Bremser — Sun, 20 Feb 2022 21:42:48 GMT

To indirectly address macro variables, use a double ampersand:

&&TopCrop&i.

In the first round of resolving, the two ampersands are reduced to one, and the macro variable i is resolved, so it is now

&TopCrop1

(if &i was 1)

In the second round, &topcrop1 is resolved as usual.

Re: How do I used a %do loop to make this code more efficient?

baroche64 — Sun, 20 Feb 2022 22:09:35 GMT

Thanks Kurt that worked! using the double ampersand and two dots:

%do i = 1 %to 5;
if Main_Farm_Commodity eq "&&TopCrop&i.." then &&TopCrop&i.._Farm = 1;
else &&TopCrop&i.._Farm = 0;
%end;