Writing Flexible Codes with the
SAS Macro Facility
(Chapter in the 7 Little SAS Book)
Animal Science 500
Lecture No. 7
September 21, 2010
IOWA STATE UNIVERSITY
Department of Animal Science
SAS Macro Development
 SAS
Macros used to be utilized by “more
advanced” SAS Users
 Today
SAS Macros are being used by more
and more people



Including beginners
Using existing Macros
Developing your own Macros
IOWA STATE UNIVERSITY
Department of Animal Science
General Macro Knowledge
 Macros
typically take longer to write and debug
than a normal SAS program that you might only
use a few times
 After

Macros are developed
Make developing maintaining a “production” program that is
used a great deal easier
1.
2.
You can have SAS make a change in one part of your program and
have SAS “echo” that throughout the rest of the program
Allows you to write a piece of SAS code and reuse it several times
either the same day or days later
IOWA STATE UNIVERSITY
Department of Animal Science
The Macro Processor
 Compiling
“submitting your code” your SAS
program is different than when submitting a
SAS Macro


Your standard SAS code is submitted and immediately
executed
Macros have an additional step


SAS passes the Macro statement to the macro processor which
“resolves” your macros that generates standard SAS code
Called meta programming because you write a program that
writes a program
IOWA STATE UNIVERSITY
Department of Animal Science
Macros and macro variables
 SAS
1.
2.
macro code has two parts
Macros
Macro variables

Name of the Macro is prefixed with a %

Name of the Macro variables is prefixed with an &

Is like your variable in a data set except it is not associated
with a data set and it is always a character variable

Can be



A variable name
A numeral
Any text you want substituted into your program
IOWA STATE UNIVERSITY
Department of Animal Science
Macros and macro variables

Macro is a larger piece of program that may
contain complex logic



Data
Proc Statements
Macro Statements





%Do
%End
%IF%Then/
%Else
IOWA STATE UNIVERSITY
Department of Animal Science
Macros
 Macro


variable can have different “scopes”
Local – defined within the macro
Global – macro code that is outside of the macro
-
Use global macro variable anywhere in your
program
-
A local macro variable can only be used inside
the macro
-
Cannot have a global and local macro variable
with the same name.
IOWA STATE UNIVERSITY
Department of Animal Science
Invoking or Turning on the Macro Processor

Must turn on the MACRO system option in order
to use it


Macro is usually on by default
May be turned off – especially true on mainframe computer
systems (usually seen in larger businesses, ISU has what
some would consider a mainframe but not used by general
students


SAS runs faster if it does not have to check and see if there are
macros are present
If MACROS are turned off that means SAS does not have to check
for them
IOWA STATE UNIVERSITY
Department of Animal Science
Invoking or Turning on the Macro Processor
 To
check and see whether the MACRO option
is on use the following SAS code:
PROC OPTIONS OPTION = MACRO;
RUN;
QUIT;

Examine the SAS log

If you see
the option MACRO then the macro processor is turned on
2.
NOMACRO the macro is turned off and you need to specify the
MACRO option at invocation or in a configuration file
* Specifiying this type of option is system dependent - check your
SAS Help and Documentation for your operating system
1.
IOWA STATE UNIVERSITY
Department of Animal Science
Substituting Text with Macro Variables
 Suppose
you have a SAS program that you run
once a week
 Each
time you run the program you have to
edit the program so it will select data for the
correct range of dates and print the correct
dates in the title


Time consuming
Errors frequently happen and then are correct (even
time consuming) or you send a report that has errors
(bad image)
IOWA STATE UNIVERSITY
Department of Animal Science
Substituting Text with Macro Variables
 Can
use a MACRO variable to insert the
correct date;
 Using
the macros in this manner allows a
much less experience person to generate the
report –

The person does not have to know SAS code because
the changes are made automatically
IOWA STATE UNIVERSITY
Department of Animal Science
Substituting Text with Macro Variables
 When
SAS encounters the name of a macro
variable, the macro processor replaces the name
with the value of that macro variable.
 Simplest
way to do this:

Use the Macro called %Let

General form %Let macro-variable-name = value
The macro-variable-name must follow normal SAS rules




32 characters or less
Start with a letter or _
Contain only letters, numerals, or underscores.
IOWA STATE UNIVERSITY
Department of Animal Science
Substituting Text with Macro Variables


General form %Let macro-variable-name = value
The macro-variable-name must follow normal SAS rules





32 characters or less
Start with a letter or _
Contain only letters, numerals, or underscores.
value is the text that is substituted for the macro variable
name can be longer than you will ever need 64,000
characters long
The following statements each create a macro variable
 % Let iterations = 10;
 % Let country = New Zealand;
IOWA STATE UNIVERSITY
Department of Animal Science
Substituting Text with Macro Variables

The following statements each create a macro variable
 %Let iterations = 10;
 %Let country = New Zealand;
** Notice that unlike ordinary assignment statement
like infile, value does not need quotation marks (‘
’ or “ ” )
** Except for the blanks at the beginning and end,
which are trimmed, everything between the
equals sign and the semicolon becomes part of
the value for that macro variable
IOWA STATE UNIVERSITY
Department of Animal Science
Using a Macro Variable

To use a macro variable you just add the & sign (ampersand) and
stick the macro variable name wherever you want its value to be
substituted.

The macro processor doesn’t look for macros inside single
quotation marks to get around this you must use double
quotations “ ”.

Do i = 1 to &iterations;

TITLE “Addresses in &country”;

After being resolve by the macro processor, these statements
would result in the following:

Do i = 1 to 10; (the 10 came from code on previous slide)

Title “Addresses in New Zealand”;
IOWA STATE UNIVERSITY
Department of Animal Science
Adding Parameters to MACROS
 Prolog


Macros allow you to use the same set of statements
over and over
Parameters are macro variables whose value you set
when you invoke a macro
IOWA STATE UNIVERSITY
Department of Animal Science
Example
A
macro named %QUARTERLYREPORT might
start like




%MACRO quarterlyreport (quarter= , salesrep = );
This macro has two parameters &QUARTER and
&SALESREP.
You invoke the macro with the following statement
%quarterlyreport (quarter=3, salesrep=smith)
IOWA STATE UNIVERSITY
Department of Animal Science
Example
 Suppose
the grower often needs a report
showing sales to an individual customer and
then sort the results. The data contain the
customer ID, date of sale, variety of flower, and
quantity.
IOWA STATE UNIVERSITY
Department of Animal Science
Data
-------+--------1--------+--------2--------+--------3
240W
02-07-2000
GINGER
356W
02-08-2000
HELICONIA
60
356W
02-08-2000
ANTHURIUM
300
188R
02-11-2000
GINGER
24
188R
02-11-2000
ANTHURIUM
24
240W
02-12-2000
PROTEA
180
356W
02-12-2000
GINGER
240
IOWA STATE UNIVERSITY
Department of Animal Science
120
Program
%LET flowertype = Ginger;
* Read all the flower sales data and subset with a macro variable;
DATA flowersales;
INFILE ‘c:\mydocuments\sales\sales.dat’;
INPUT CustomerID $4 @6 Saledate MMDDYY10. @17
Variety $9. Quantity;
IF Variety = “&flowertype”;
Run;
Quit;
* Invoke a macro to Print the report using a macro variable
PROC PRINT DATA = flowersales;
FORMAT Saledate WORDDATE18.;
TITLE “Sales of &flowertype”;
Run;
Quit;
IOWA STATE UNIVERSITY
Department of Animal Science
Output from Macro Example
Sales of Ginger
Customer
Obs
ID
1
240W
2
3
SaleDate
Variety
Quantity
February 7, 2008
Ginger
120
188R
February 11, 2008
Ginger
24
356W
February 12, 2008
Ginger
240
IOWA STATE UNIVERSITY
Department of Animal Science
Program
* Macro with parameters
%MACRO select (customer=, sortvar=);
PROC SORT DATA = flowersales OUT = salesout;
BY &sortvar;
WHERE CustomerID = “&customer”;
PROC PRINT DATA = salesout;
FORMAT SaleDate WORDDATE18.;
TITLE “Orders for Customer Number &customer”;
%MEND select;
IOWA STATE UNIVERSITY
Department of Animal Science
Output looks like this:
Orders for Customer Number 356W 1
Customer
OBS
ID
SalesDate
Variety
Quantity
1
356W
February 8, 2000
Anthurium
300
2
356W
February 12, 2000
Ginger
240
3
356W
February 8, 2000
Heliconia
60
Orders for Customer Number 240W 2
Customer
OBS
ID
SalesDate
Variety
Quantity
1
240W
February 7, 2000
Ginger
120
2
240W
February 12, 2000
Protea
180
IOWA STATE UNIVERSITY
Department of Animal Science
Creating Modular Code with Macros
 If
you are writing the same or similar SAS
statements over and over consider using a
Macro.

You can package a piece of bug free code and use it
repeatedly within the same SAS program or in many
programs
 %Macro
and %Mend can be thought of as a
sandwich

You can put anything you want
IOWA STATE UNIVERSITY
Department of Animal Science
Creating Modular Code with Macros
 %Macro
and %Mend can be thought of as a
sandwich


You can put anything you want
General form is:
%MACRO macro-name; (tells SAS it’s the beginning of a Macro)
macro-text
%MEND macro-name;
(tells SAS it’s the end of a Macro)
Macro-name is a name you can make up
up to 32 characters
start with a letter or _
contain only letters, numerals, and underscores
IOWA STATE UNIVERSITY
Department of Animal Science
Creating Modular Code with Macros
 %Macro
and %Mend can be thought of as a
sandwich


You can put anything you want
General form is:
%MACRO macro-name; (tells SAS it’s the beginning of a Macro)
macro-text
%MEND macro-name;
(tells SAS it’s the end of a Macro)
Macro-name is a name you can make up
up to 32 characters
start with a letter or _
contain only letters, numerals, and underscores
IOWA STATE UNIVERSITY
Department of Animal Science
Creating Modular Code with Macros

General form is:
%MEND macro-name;
 The macro-name in the MEND statement is
optional.
 Macros will be easier to debug or remove errors
if the macro-name is included in the MEND
statement
 Easier to match MACRO and MEND statements
makes the sandwich complete
IOWA STATE UNIVERSITY
Department of Animal Science
Macros
 Macros
can be stored in a central location
called an autocall location



Can be used multiple times in different programs by a
single programmer
Can be used by multiple programers if they have access
to a centrally stored autocall location as long as they
have access or permission
Easy way to store macros that might be useful multiple
times by a single or multiple users
IOWA STATE UNIVERSITY
Department of Animal Science
Macros
 Macros


can have multiple parameters
Same report but with a different set of data
Example

%Macro macro-name (parameter-1= , parameter-2 ,
parameter-n= );
Macro-text;
%MEND macro-name;
Example: A macro named %QUATERLYREPORT might start like this;
%Macro quarterlyreport (quarter= , salesrep= );
Could invoke Macro by the following statement;
%quarterlyreport (quarter=3,salesrep=Smith);
IOWA STATE UNIVERSITY
Department of Animal Science
Macros
 Likely
will not use macros a great deal with
one exception
A

macro called PDMIX
Separates means from a Proc Mixed analysis with a
user defined separation technique


Duncans, Tukeys, etc.
Assigns letter names to separated means of one or
more class variable defined in a Proc Mixed analysis
IOWA STATE UNIVERSITY
Department of Animal Science
PDMIX macro
PURPOSE: This macro takes two data sets from Proc
MIXED (Version 8), created by the DIFFS option on the
LSMEANS statement. If an ADJUST= option is used,
the pdiffs from this are used, not the unadjusted
defaults. The pdiffs are converted to groups, labeled
by numbers, and this is merged onto the lsmeans data
set. The numbers are converted to letters, and for
cases where more than 26 letters are needed, sections
of letters are coded. For example, 3 means might have
the letters A, (2)A, and (3)A. These 3 means are all
different, because although all have the letter A, each
A belongs to a different section, identified by (#).
IOWA STATE UNIVERSITY
Department of Animal Science
Example use of PDMIX Macro
Example of use. Assume the file pdmix800.sas,
containing the macro code, is on the a: drive. Then the
code below will run MIXED, and run pdmix800 on the
lsmeans. MIXED is told not to print the means and
pdiffs, using the ODS exclude statement, as pdmix800
does the printing in the more desirable format. Also
shown are two optional parameters.
IOWA STATE UNIVERSITY
Department of Animal Science
Example use of PDMIX Macro
Proc Mixed;
class block a b;
model y = a b a*b;
random block;
lsmeans a b a*b/pdiff;
ods output diffs=ppp lsmeans=mmm;
ods listing exclude diffs lsmeans; run;
%include 'a:pdmix800.sas';
%pdmix800(ppp,mmm,alpha=.01,sort=yes);
IOWA STATE UNIVERSITY
Department of Animal Science