topic Re: Question about macro language in SAS Programming

Question about macro language

Onizuka — Mon, 15 Apr 2019 12:28:20 GMT

Hello everyone,

I'm working on SAS Macros and I saw that sometimes, we have to put

%THEN %DO.....

but sometimes we don't have to.

For example :

DATA mdv.&typequest._finale (where = (test <> 0)) ;
	SET mdv.&typequest._finale;
	ARRAY tquestcourt[&nbvar.] &list.;
	test=0;
	%LOCAL i ;
	%DO i=1 %TO &nbvar.;
		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ;
	%END;
RUN;

On this example, there is a %do i ... %to but just below there isn't a %if %then %do.

I didn't find specific rules on the web so I would like to ask the question here.

Thank you very much 🙂

Onizuka

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 12:04:43 GMT

%DO and %IF are independent, one does not have to follow the other, you use them as needed.

In the code you show, there is no need for a macro %DO here, and it won't work as you have coded it anyway. You can use a data step DO to loop over the array.

IMPORTANT CONCEPT: get code to work properly first, one one iteration through a small data set, without macros; and then and only then add in macros and macro variables. Since you can get this code to work without %DO by using the data step DO, no need for macros.

Re: Question about macro language

Amir — Mon, 15 Apr 2019 11:22:34 GMT

Would you please provide an example of working code where a %do is followed by a %then.

Thanks,

Amir.

Re: Question about macro language

Quentin — Mon, 15 Apr 2019 11:47:17 GMT

You typically wouldn't have %do followed by %then. You will often see %then followed by %do, e.g.

%if <condition> %then %do;
  *something;
%end;

As @PaigeMiller wrote, the %DO statement is a separate statement than the %IF/%THEN/%ELSE statement.

There are plenty of examples in the documentation, see e.g.

https://documentation.sas.com/?docsetId=mcrolref&docsetTarget=p1xhuzfc68jkhcn1xb0c4d5atq5e.htm&docsetVersion=9.4&locale=en

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 12:17:17 GMT

@Amir wrote:

Would you please provide an example of working code where a %do is followed by a %then.

I don't think code can have %DO followed by %THEN.

Re: Question about macro language

Amir — Mon, 15 Apr 2019 12:12:01 GMT

@Quentin not sure if you meant to respond to me or the OP(?)

If it was me then agreed, which is why I asked the OP for a working example, as that was their opening assertion, so either they find an example, which someone on this forum should be able to explain to the OP, or they don't, in which case part of the premise of the question does not hold true and so the OP realises their assumption. Win-Win!

Kind regards,

Amir.

Re: Question about macro language

Amir — Mon, 15 Apr 2019 12:14:08 GMT

@PaigeMiller agreed. Please see my initial response to @Quentin.

Kind regards,

Amir.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 12:18:40 GMT

Hello Miller, thank you for you response.

Before start doing "macro programm" i'm always doing without macro (like you said).

I'm a little surprise by what you say because the programm works well !

This one allows to keep the observations for which at least one variable in the list is not null.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 12:35:17 GMT

I don't have an example of that, the example i have is which one I post on the topic :

	%DO i=1 %TO &nbvar.;
		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ;
	%END;

You can see the %DO ... %TO and just below an IF (without percent before) ... THEN (without percent before) do (without percent before) so I was wondering why sometimes we put the %(IF, THEN, DO) and why sometimes not. Just after the %DO i = 1 %to &nbvar. ; there is a IF THEN DO without percent but as I am in macro language i found it weird.

EDIT : This example is from a "long" macro programm

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 12:27:08 GMT

I agree, the %DO comes always after the %THEN

EDIT : my bad, i write it bad on my exemple, i wanted to say %THEN ... %DO and not say %DO ... %THEN

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 12:46:08 GMT

I was wondering why sometimes we put the %(IF, THEN, DO) and why sometimes not

Because sometimes the logic of the specific program requires it, and other times the logic does not require it.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 13:01:52 GMT

Yes, I guess it depends.. buy why in my example (it's just an example of a code I have and run well) if i replace

IF tquestcourt[&i] ne . THEN do ;

%IF tquestcourt[&i] ne . %THEN %DO ;

it doesn't work while i'm in a macro programm. I don't understand very well the logic you are talking about.

Re: Question about macro language

Amir — Mon, 15 Apr 2019 13:05:42 GMT

Typically, macro code is executed before any data step code is executed.

1) The %do - %end loop will cause the data step code to be repeated &nbvar times.

2) Once the macro code has completed then the data step code will start, which include &nbvar instances of the if-then-do-end code.

3) Using options mprint; before you run the code should show more information in the log.

Amir.

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 13:14:35 GMT

Okay, @Onizuka we are going around in circles here. At one point, you seem to be asking questions about macro code, and then at other times you seem to be asking questions about the logic. Which is it?

If your code doesn't work, then show us the SAS log, using options mprint; before you run the program. Look at the log yourself and see if you can figure out what is the problem. If not, then post the log here by clicking on the {i} icon and pasting it into the window that appears. Do not -- I repeat DO NOT -- post the log without clicking on the {i} icon and pasting it into the window that appears.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 13:28:33 GMT

Thank you Amir,

I believe that I have understood. When using a variable macro the % must be used and if not removed.

I think I could have written this :

/* if i take off the macro variable */
%macro test ;
..
Data blabla;
set blabla1 ;
..      
	DO i=1 TO 10;
		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ;
	END;
..
run ;

%mend test ;

/*if i add the macro variable */ 

%macro test ;
..
Data blabla ;
set blabla1 ;
..

	%DO i=1 %TO &nbvar.; 
		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ; 
	%END;
..
run ;

%mend test ;

Am I right ? haha

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 13:28:32 GMT

@Onizuka wrote:

Thank you Amir,

I believe that I have understood. When using a variable macro the % must be used and if not removed.

I think I could have written this :
/* if i take off the macro variable */	
%macro test ;
....
Data blabla;
set blabla1
...        
DO i=1 TO 10;
		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ;
	END;
...
run ;

%mend test ;

/*if i add the macro variable */

	%DO i=1 %TO &nbvar.;
 		IF tquestcourt[&i] ne . THEN do ; 
		test=test+1; 
		end ;
	%END;
Am I right ? haha

There is absolutely no benefit to adding a macro %DO loop here when you could and should use the data step DO loop.

Re: Question about macro language

Tom — Mon, 15 Apr 2019 13:34:35 GMT

If you want to write MACRO logic then you use the macro commands: %IF, %DO etc.

If you want to write SAS logic then you use the SAS commands: IF, DO etc.

The macro processor will execute the macro logic and the resulting code (text) will be sent to SAS to interpret and execute.

When thinking about what macro logic does think about it in terms of what CODE it generates.

When thinking about what SAS logic does think about it in term of what DATA It generates.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 13:36:14 GMT

Ok, it also worked by removing the % .. I'm a little lost i have to admit

I thought that when we are in a macro program we must put % everywhere

Re: Question about macro language

PaigeMiller — Mon, 15 Apr 2019 13:48:23 GMT

@Onizuka wrote:

Ok, it also worked by removing the % .. I'm a little lost i have to admit

Data steps work just fine without any % signs. You need to become 100% clear about what the difference between macro code and data step code is.

Macro language results in text substitution. It replace some text (for example, &I) with its value (for example, 3). You don't need text substitution here, because everything written in data step language in this case works properly.

As stated earlier, get the program to work on one example or one iteration without macros and without macro variables. Then only add macros if what you need can't be done any other way.

Also

%IF tquestcourt[&i] ne . %THEN %DO ;

the %IF means that the macro processor now is NOT looking for data step variables and their values. It does not know the value of TQUESTCOURT. It thinks that tquestcourt[&i] ne . is some text string, and it does not use the data set variable values. That is why you must use IF and not %IF here.

I thought that when we are in a macro program we must put % everywhere

A terrible concept, that will mislead you and cause many problems in your future. Never think this way again. Please think about the concepts that @Tom and I and others have stated here.

Re: Question about macro language

Onizuka — Mon, 15 Apr 2019 13:44:55 GMT

Ok, so when we are in a Data step, we don't need to use %DO %IF etc. We should use the macro language when we are NOT in a data step. You agree ?

Like on this macro I have created which permit to execute my "long" macro programm :

%MACRO RUN_CIM_EER_EV (typequest =);

%LET date_fin_trim_precedent = %SYSFUNC(mdy(&mois_fin_trim_precedent.,&jour_fin_trim_precedent.,&annee_fin_trim_precedent.));
%LOCAL i ;
%DO i = 1 %TO %SYSFUNC(countw(&typequest));

%LET nextvar 	= %SCAN(&typequest, &i);		

			%CIM_EER_EV (typequest 				  = &nextvar
						,chemin_fichier			  = &chemin_fichier
						,jour_fin_trim_precedent  = &jour_fin_trim_precedent
						,mois_fin_trim_precedent  = &mois_fin_trim_precedent
						,annee_fin_trim_precedent = &annee_fin_trim_precedent)
	
%END ;

%MEND RUN_CIM_EER_EV ;