topic Re: How to resolve Macro Variable as Part of Variable Name in SAS Programming

How to resolve Macro Variable as Part of Variable Name

gxu — Tue, 06 Dec 2011 20:16:34 GMT

Hi All,

I have a question regarding to the macro variable in a variable name.

Basically, I want to decide an index which can be calculated from i and j, then I will use this index to create a variable name.

For example, in the following code, I expect the dataset doudou to contain a variable a6=1 when i=1, j=2, but it didn't work.

Do you have any idea how to solve this question?

%let i=1;

%let j=2;

%let ind=(&i-1)*18+(&j-1)*6;

data doudou;

a&ind=1;

run;

Thanks for your attention!

xgn

Peter_C — Tue, 06 Dec 2011 21:41:28 GMT

&ind is a string

OK it contains an expression

when you want it evaluated, you need to do something

otherwise

a&ind is passed to the compiler as

a(&i-1)*18+(&j-1)*6

Then it has to decide if a( implies an array reference or a (probably user) function.

If you wanted

then you must encourage the evaluation of the expression in &ind

Perhaps %eval( &ind ) might achieve what you want

as in

23   %let i=1;
24   %let j=2;
25
26   %let ind=(&i-1)*18+(&j-1)*6;
27
28   data doudou;
29      a%eval(&ind)=1;
30      putlog _all_ ;
31   run ;

a6=1 _ERROR_=0 _N_=1
NOTE: The data set WORK.DOUDOU has

OK?

gxu — Tue, 06 Dec 2011 22:33:07 GMT

Peter,

Yes, it works, thank you! P.S, I didn't know %eval before, it seems it's very useful for my future work.

Best regards,

xgn

Tom — Wed, 07 Dec 2011 00:25:10 GMT

Probably this code is just a simplified version of what you are really doing, but it does not look like an application for a macro arithmetic.

Seems it would be more appropriate to just write it in SAS rather then using the macro language to generate SAS code.

data doudou;
  i=1;
  j=2;
  set mydata;
  array a a:;
  a((i-1)*18+(j-1)*6)=1;
run;

Or perhaps you need a two dimension array?

data doudou;
  i=1;
  j=2;
  set mydata;
  array a(18,6) a:;
  a(i,j)=1;
run;

gxu — Wed, 07 Dec 2011 14:49:31 GMT

Hi Tom,

You are right. The above code is just a simple version of what I am going to do. I will also try your methods. Thank you so much!

Best regards,

xgn