Hi I am not familiar with the kind of macro where there is a % before a lot of words, what do they mean?
%macro gen_ind(num); %do i=1 %to &num %by 1; proc sql; create table rate_MAC as select a.*, . . . Quit; %end;
Hi @HeatherNewton,
I recommend Chapter 1 "Introduction to the Macro Facility" in SAS 9.1 Macro Language.
I Think it's to difficult to explain yout example in two sentences.
Best, Markus
before I saw example where % are only added to %macro and %mend...
why suddenly they are added to do if then this kind of word?
@HeatherNewton wrote:
before I saw example where % are only added to %macro and %mend...
why suddenly they are added to do if then this kind of word?
Because these are macro statements. Please read the documentation.
In the link I gave you, go to Understanding and Using the Macro Facility. This will help you understand what the macro facility does.
Hi @HeatherNewton,
p.8. of the docu:
Conditionally creating SAS code gets to the point! It's an advanced concept. For me it helped to take the course SAS Training in the United States -- SAS® Macro Language 1: Essentials
am I right to say if these if then else loops in within a macro program, it needs % added to if then else?
if the if then else condition is not inside a macro program, then no % is required in from of if then else...
"&" and "%" are macro triggers which invoke the macro processor, or tell the macro processor that the following is (&) a macro variable/parameter reference , or (%) a macro statement or macro/macro function call. Everything else is just text to the macro processor.
You must first understand what the macro processor does. It is a code generator that allows you to create dynamic code. For easier understanding, its elements look a lot like "standard" SAS elements, but they are (in fact) completely different things.
IF and %IF are completely different things, although they have similarities, but THEY ARE DIFFERENT.
Same for (e.g.) SUBSTR vs. %SUBSTR.
Imagine you want to run a code for datasets that span back before Austria changed to the Euro, but, in case an "old" dataset is encountered, add a conversion to your code:
%if &year. lt 2002
%then %do;
amount = amount / 13.7604;
%end;
The first line compares the macro variable year to a value (mind - NOT a data step variable!!). If that comparison results in TRUE, the following %DO-%END block is executed by the macro processor, so it creates the code
amount = amount / 13.7604;
and feeds it back to the SAS data step compiler. In case you run the analysis for a later year, the statement is not created, and the data step compiler never sees it.
if year lt 2002
then do;
amount = amount / 13.7604;
end;
This code does not invoke the macro processor, is "seen" by the data step compiler, and uses the data step variable year to make the comparison; the IF is always executed during data step runtime.
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