introduction to sas macro language

8/14/2019 Introduction to SAS Macro Language

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I n t roduc t i on to

SAS Mac ro Language

Bios 524: Biostatistical Computing

Bios 524: Introduction to SAS Macro Language 2

Get t ing He lp !

Use the SAS OnLine Documentation for

help on this subject. Follow this path:

l Base SAS Software

l SAS Macro Language Reference

l Introduction follow these pages to learn aboutthe macro facility

l Macro Language Dictionary find help on allmacro statements, functions, etc.


What i s t he SAS Mac r o

F ac i l i t y?

From the OnLineDoc:

l The macro facility is a tool for extending andcustomizing the SAS System and for reducing theamount of text you must enter to do commontasks.

l The macro facility allows you to assign a name tocharacter strings or groups of SAS programmingstatements. From that point on, you can work with

the names rather than with the text itself.


What i s t he SAS Mac ro

Fac i l i t y?

From the OnLine Doc:

l When you use a macro facility name in aSAS program or from a command prompt,the macro facility generates SASstatements and commands as needed.

l The rest of the SAS System receivesthose statements and uses them in the

same way it uses the ones you enter in thestandard manner.


What i s t he SAS Mac r o

F ac i l i t y?

Two components

l Macro Processor

l This compiles your macro and integrates it withyour SAS job.

l Macro Language

l This is how you communicate with the macroprocessor.


T r igge ri ng t he Mac r o

Pr ocesso r

Two delimiters will trigger the macroprocessor in a SAS program

l &namel This refers to a macro variable. The current

value of the variable will replace &name.

l %namel This refers to a macro, which may generate a

section of a statement, one or more completeSAS statements, or even whole data or procsteps.


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Defin ing and Using Mac ro

Variab les

%let

l Example%let keyvar = DOEntry;

libname library "c:\bios524\classlib";

proc print data=classlib.clinics;

id clinicid;

var &keyvar;

proc freq data=classlib.clinics;

tables &keyvar;

run;

DOEntry is assigned to

macro variable keyvar.Leading and trailing

blanks are ignored.

As the proc

step is

compiled,

&keyvar isreplaced with

DOEntry.


Mac ro Var iab le Va lues

Values are character strings

No distinction is made between numeric and

character type.l However, see the macro function %eval.

Embedded special symbols require the use ofa macro quote function when assigning orusing macro variables.

l See macro functions %str, %nstr, %quote,%nquote, to mention a few.


Rec ogn iz ing a Mac ro

Var iab le

The key is the leading &.

SAS views &leadvar and &leadvar1as twodifferent macro variables.l %let leadvar = x;

l &leadvar resolves to x.

l &leadvar1 is not resolved to x1. An error message mayappear.

When the end of the macro variable is not clear,

delimit it with a .l &leadvar.1 resolves to x1.

l Note: &leadvar..1 resolves to x.1.


Resolv ing Mac ro

Var iab le w i th in Quo tesExamplel %Let project = Assignment 4;

l Title Results for &project;l Resolves to Results for &project .

l Title Results for &project;l Resolves to Results for Assignment 4 .

Example%Let refd = 01JAN2000;

%Let dob = 12APR1955;age = int((intck("month","&dob"d,"&refd"d) -

(day("&refd"d)


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SAS Mac ros

Define a SAS macro using the basic

syntax

Example

Usage:

%MACRO macro-name ;

macro definition%MEND macro-name ;

%macro whereby;

where (age ge 18 and eligible=1);

by ClinicId;

%mend whereby;

proc print data=Clinics;

%whereby

run;


Pr o d u c i n g SA S c o d e w i t h

M a c r o s

%DO%TO; %END;%macro loopit;

%let var1 = Age;

%let var2 = Height;%let var3 = Weight;

%do i = 1 %to 3;proc means;

var &&var&i;Title "Analysis for the Variable &&var&i";

%end;

%mend loopit;

data one;input age height weight @@;datalines;

34 60 130 45 70 201 50 68 188;

%loopitrun;

First time through the

loop:

1. Resolves to &var1

2. Resolves to Age

This generates:

proc means;

varAge;

Title "Analysis for the

Variable Age";

proc means;

var Height;Title "Analysis for the

Variable Height";

proc means;

varWeight;

Title "Analysis for the

Variable Weight";


Produc i ng SAS c ode w i t h

M a c r o s

%IF%THEN; %ELSE;

%macro wantrslt;

%let results = %upcase(&giverslt);

%if &results = YES %then %do;

proc means;var _numeric_;Title "Results for Numeric Variables";

%end;

%else %put No results requested; %* Appears in log;

%mend wantrslt;

%let giverslt = NO;

%wantrslt

Convert to

upper case

Placestext in

SAS log.

Macrocomment


Pass ing Paramet e rs t o

Macros

Character values may be passed to

parameters that are local macro

variables.

Syntax %MACRO macro-name (parm1, parm2, , pa rmk);macro definition

%MEND macro-name ;



MacrosExample

%macro wantrslt (giverslt);

%let results = %upcase(&giverslt);

%if &results = YES %then %do;

proc means;var _numeric_;Title "Results for Numeric Variables";

%end;

%else %put No results requested; %* Appears in log;

%mend wantrslt;

%wantrslt(no);

%wantrslt(yes);

Local macro variable

giverslt is defined.

Values are passed to the

local macro variable

giverslt .



Macros : An A l te rna t i ve

MethodCharacter values may be passed to

named parameters.

l The named parameters may be placed inany order.

l If omitted, the parameter receives a defaultvalue (that may be null).

%MACRO macro-name (parm1=deflt1, parm2=deflt2, , par mk=defltk);

macro definition

%MEND macro-name ;


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Macros : An A l te rna t i ve

MethodExample

%macro agecalc (dob=, refd=01JAN2000);

%if &dob= %then %do;%put Date of birth is missing;

age = .;

%end;

%else

age = int((intck("month","&dob"d,"&refd"d) -

(day("&refd"d)


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Macro Er ro r Messages

and Debugg ing

OnLine Documentation

l Errorshttp://www.at.vcu.edu/manuals/sas/sashtml/macro/z1302436.htm

l Debugginghttp://www.at.vcu.edu/manuals/sas/sashtml/macro/z1066200.htm


Se lec t Macro Func t ions

and Ca l l Rout ines

CALL SYMPUT(macro-variable,value);l http://www.at.vcu.edu/manuals/sas/sashtml/macro/z0210266.htm#znid-364

l

Cautions:l A macro reference resolves when the data or proc step is

compiled, but symput assigns a value to the macro variable

during execution. Thus you cannot refer to that macro

variable in the same step.

SYMGET(argument)l http://www.at.vcu.edu/manuals/sas/sashtml /macro/z0210322 .htm

l Use this to assign the value of a macro variable to a data step variable. Thisassignment takes place during execution.

introduction to sas macro language

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