Ask Analytics: Conditional Execution in Macro

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By conditional Execution, I mean : Select and run the parts of code on the basis of certain logic. We use "If" "else" for logical operations in macros :

A SAS Macro with IF - ELSE condition looks like :

%Macro Macro_name( a,b,c);

%IF expression %THEN %DO;
..................................
..................................
%END;

%ELSE %DO;
..................................
..................................
%END;

%Mend;
%Macro_name( 4,5,6);

Let's learn it by an example.

Consider the data set :

Data Class;

infile datalines ;

Input Name $ Subject $ full_marks Marks_secured;

cards;

Rajat Maths 100 52

Vinod Maths 100 64

Rakesh Maths 100 57

Geeta Maths 100 58

Bharat Maths 100 86

Rajesh Maths 100 81

Monal Maths 100 67

Aarya Maths 100 88

Ritesh Maths 100 68

Neha Maths 100 88

Rajat English 150 53

Vinod English 150 69

Rakesh English 150 52

Geeta English 150 59

Bharat English 150 88

Rajesh English 150 59

Monal English 150 71

Aarya English 150 66

Ritesh English 150 68

Neha English 150 77

;

Run;

Now we want to roll up this data at two levels :
1. Student Level
2. Subject Level.

It's just a matter of two PROC SQL queries, I know ... But still we would do it with Macro, just for the sake of learning.

Solution without Macro :

Proc SQL;
Create table student_wise as select name, sum(full_marks) as full_marks, sum(Marks_secured) as Marks_secured
from class
group by name
order by name;
Quit;

Proc SQL;
Create table Subject_wise as select Subject, sum(full_marks) as full_marks, sum(Marks_secured) as Marks_secured
from class
group by Subject
order by Subject;
Quit;

Let's now do it with a simple macro

%Macro Simple (Report_type);

Proc SQL ;

Create table &Report_type._wise as

Select &Report_type., sum(Marks_secured) as sum_secured, sum(full_marks) as sum_total

from class

group by &Report_type.

order by &Report_type.;

Quit;

%Mend ;

%Simple (Subject);

%Simple (Name);

Let's now use a macro with "IF"s

%macro understand_if_then(Report_type);

%if &report_type. = Name %then %do ;

Proc SQL ;

create table student_wise as

select name, sum(Marks_secured) as sum_secured, sum(full_marks) as sum_total

from class

group by name

order by name;

Quit;

%end ;

%else %if &Report_type. = Subject %then %do ;

Proc SQL ;

create table subject_wise as

select Subject, sum(Marks_secured) as sum_secured, sum(full_marks) as sum_total

from class

group by Subject

order by Subject;

Quit;

%end ;

%Mend ;

%understand_if_then(Subject);

%understand_if_then(Name);

How the above code works ?

The above execution can be checked in SAS log, with enabler options MPRINT MLogic;

To know more about these options read >>> Useful options and tips whiles writing SAS Macros