SAS Macros
A. Dhandapani
Pi i lS
Principal
Scientist
i ti t (St
(Statistics/Computer
ti ti /C
t A
Applications
li ti
National Academy of Agricultural Research
Management
Rajendranagar, Hyderabad 500 407
dhandapani.appavoo@gmail.com
p
pp
@g
SAS Macros
Useful for reducing SAS Codes
Ease of doing reports/analysis which are
frequently required
C
Complex
l analysis
l i which
hi h require
i use off
many types of analysis – simplified into
macros (like statistical genetics analysis)
Facilitate passing information from one
procedure to another
SAS Macro Example 1
%lett myname = A.
%l
A Dh
Dhandapani;
d
i
Title1 “Output from a macro by &myname”;
P
Proc
print
i t data=sashelp.class;
d t
h l l
Run;
Example 1: Output (part)
SAS Macro variables
Nothing but text values
Any text can be assigned to a macro
variable
%l t <macrovariablename>
%let
i bl
= <value>;
l
Statement
State
e t assigns
ass g s the
t e value
a ue to tthe
e macro
ac o
variable
Macro variable
ariable can be used
sed an
anywhere
here in
SAS Code using &macrovariable
Symbols % and &
Macro language statement starts with a
sign
g %
Macro variable references start with a
symbol &
Example 2
Task: Create a report to compute
treatment means for a location
Data File to use: Combined
Variables:
V i bl
lloc, ttreat,
t S
Syield
i ld
Example 3
Macro Reports() – Prints treatments from
all locations
Example 4: Using System
Variables
Several System variables are available
such as
– &sysdate
– &systime
– &sysday
Example 4 shows use of sysdate and
sysday op
option
o in footnote
oo o e sstatement
ae e
Macro Variables
 Macro variable can be referenced
anywhere
y
in the SAS Program
g
other than
data lines
 Macro variable can be used in open
statement as well as within a macro
program
 Macro variable can be created by SAS
and by your programs
Macro Variables
 Macro variable can be global or local
 Macro variable values are text
 Name assigned to a macro variable must
b a valid
be
lid SAS N
Name
Defining and using Macro variables
%lett ttreatment
%l
t
t = ttreat;
t
PROC GLM DATA=crd;
CLASS &t
&treatment;
t
t
%let statement defines a macro variable called
treatment and assigns the value treat
&treatment would be replaced by treat, when
the code runs
Using single and double quotes
T reference
To
f
a macro variable
i bl iin a string,
ti
use d
double
bl
quotes.
Example:
Correct statement:
Title1 “Treatment
Treatment Means for &loc”;
&loc ;
Incorrect:
Title1 ‘Treatment Means for &loc’;
This will print title as:
Treatment Means for &loc
%put statement
%put statement prints the value of the
macro variable name in LOG file
Useful for trouble shooting/debugging
E
Example5.sas
l 5
SYMBOLGEN
OPTION SYMBOLGEN;
Prints the value of the macro variable as
resolved by SAS in LOG file
T turn
To
t
off,
ff use
OPTION
O
O NOSYMBOLGEN;
OS
O G ;
Example6
Exercise: Find out the values
%let compute = 12 *43;
%let value1 = 30;
%let value2 = 20;
%let value3 = value1 + value2;
% let company = “SAS
SAS && Co”;
Co ;
Title1 “The value3 is &value3”;
Title1 ‘The value3 is &value3’;
Placing text BEFORE a macro
variable
%let number = 1;
%let independent = X&number;
Independent is resolved into X1
No need of any special symbol, if any
prefix
p
e is
s to be added to a macro
ac o variable
a ab e
value. (Here X is added to macro variable
value 1)
Placing text AFTER a macro
variable
To add value and the end of a macro variable
value, . (dot) is used
Example(( Wrong)
Example
%let independent = loc;
Proc Print Data = dset;
Var &independent1 &independent2;
Run;
Interpreted as two macro variable, independent1
and independent2 not as loc1 & loc2
Placing text AFTER a macro
variable
Example( Correct)
Example(
p
= loc;
%let independent
Proc Print Data = dset;
.
.
VAR &independent 1 &independent 2;
Run;
Use of dot makes VAR statement resolves into
VAR loc1 loc2;
Referring a library
%let mylib = training;
PROC PRINT DATA = &mylib.crd;
&mylib crd;
&mylib.crd resolves into
trainingcrd
To resolve correctly, use
PROC PRINT DATA = &mylib..crd;
Use of &&
%let number = 1;
%let val1 = section;
%let doubleand = &&val&number;
&& forces SAS to evaluate twice
First Pass: &val1
Second Pass:section
Developing a Macro
General Syntax is:
%macro <name> (<params>);
…
%mend;
To call a macro, invoke,
%<name> (<params>);
Running a macro
Submit the code containing macro first and
invoke it later ((Macro will be available for
that session only)
Place the program containing macro code
into certain folder (called autocall) –
Available whenever desired
Use include statement
Macro without parameters
Example 9:
Here global variable is used and macro code
is submitted before invoking it.
Example
a p e 10:
0 ((include
c ude state
statement.sas)
e t sas)
Use include statement to include the macro
and in
invoke
oke it
Macros with parameter
Any number of parameters can be defined
in a macro p
program
g
Parameters are separated by commas
Th order
The
d and
d number
b off parameters
t
should be same while invoking the macro
Example 11:Macro with one parameter
Macros with default parameter
values
Macro may have parameters having default
value
Defined as parameter name = value
If it is not specified, default value is used
Example 12
First option invokes with both parameter values
Second option invokes with one parameter
Exercise: How to create a macro?
Problem:
P
bl
C
Create
t a generall macro ffor RBD
Step 1:
Write a code to do the analysis
Step 2:
Identify parameters
Step 3:
Replace the parameter with macro variables
Step 4:
Create Macro statement
Step 5:
Check it
To move further
%do-%end, %while%do%while-%end statements
%if %then %else statements
Proc SQL & Macro – useful for retrieving
i f
information
ti ffrom output
t t tables
t bl
SAS
S S Help
ep
Book:SAS Macro Programming Made
Easy
Eas 2nd Edition (2007) b
by Michale M
M.
Burlew, SAS Press