Lesson 9, Part 1a: Macro Facility Basics and Macro Variables¶

  • Components of macro facility
  • Ways to create macro variables
  • Creating macro variables with the %LET statement
  • Displaying macro variable values

Jupyter Python Notebook Keyboard Shortcuts and Text Snippets for Beginners

Macro Facility¶

The SAS macro facility is a text substitution facility for reducing the amount of text that you must enter to do common tasks.

More specifically, the macro facility does the following:

  • Displaying system information
  • Symbolic substitution within the SAS code
  • Automated production of SAS code (automation for repetitive tasks)
  • Conditional construction of SAS code
  • Dynamic generation of SAS code (data-driven applications)

Macro Facility = Macro Processor + Macro Language

The macro processor does the actual macro processing. Macro language is the syntax used to communicate with the macro processor.

Macro Triggers (& and %)¶

The macro trigger (ampersand or &), followed by a name, references a macro variable:

&dsn
&group
&yea

The macro trigger (percent sign or %), followed by a name, references a macro program, a macro statement, or a macro function.

Macro name¶
%dsn
%group
%year
Macro statement¶
%do year = 2010 %to 2020;
Macro function¶
%substr(&date,6,4)
In [1]:
from IPython.display import Image
Image("C:/Data/Macro_Facility.png")
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Macros vs. Macro variables¶

Slaughter, SJ, and LD. Delwiche. SAS (R) Macro Programming for Beginners, SUGI

A macro variable

  • contains values that are text, with a length ranging from 0 to 65534 characters
  • is referenced with an ampersand (&) in different parts of the SAS program
  • can be interpreted as a number if used in a context that requires one (See the example below)
  • stored in a memory area called the global symbol table, not in a data set
Interpretation of macro variables - Code Example 1¶
In [13]:
ods html close;
options Options nocenter nodate notes nosource nonumber nosymbolgen;
%let year=2018;
data test;
 x=&year;
 y="&year";
run;

The SAS System


NOTE: The data set WORK.TEST has 1 observations and 2 variables.
NOTE: DATA statement used (Total process time):
      real time           0.04 seconds
      cpu time            0.00 seconds
      

The SAS System

E3969440A681A2408885998500000015
Interpretation of macro variables - Code Example 1 (Continued)¶
In [16]:
ods html close;
options Options nocenter nodate nonotes nonumber nosymbolgen;
proc sql; 
 select varnum, name, type 
	from dictionary.columns 
	where libname = 'WORK' and memname = 'TEST'; 
quit;
SAS Output

The SAS System

Column Number in Table Column Name Column Type
1 x num
2 y char

When resolved, SAS decides what type of variable it is based on the context in which it is used. In the example above, x is numeric while y is a character variable when resolved.

Advantage of code substitution using macro variables.¶

Instead of repeating the same piece(s) of text in your SAS program, you can create macro variables by:

  • assigning that text to a macro variable [%LET DS = CLASS;] once
  • and then just referencing it [&DS] at different parts of your SAS program without you having to type the same text over and over again.

The value of the macro variable could be:

  • data set name
  • data value
  • variable name
  • SAS statement
  • part of the SAS statement
In [11]:
from IPython.display import Image
Image("C:/Data/Ways_to_create_macro_vars.png")
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No description has been provided for this image

Macro variables

  • Automatic macro variables (automatically created by the macro processor)
  • User-defined macro variables (i.e., defined by the macro programmer)

Below are the two examples of user-defined macro variables.

In [9]:
ods html close;
options nocenter nodate nonumber;;
data _null_;
  current_date = date();
  format  current_date worddate.;
 put current_date=;
run;

The SAS System

359        ods listing close;ods html5 (id=saspy_internal) file=_tomods1 options(bitmap_mode='inline') device=svg style=HTMLBlue;
359      ! ods graphics on / outputfmt=png;
NOTE: Writing HTML5(SASPY_INTERNAL) Body file: _TOMODS1
360        
361        ods html close;
362        options nocenter nodate nonumber;;
363        data _null_;
364          current_date = date();
365          format  current_date worddate.;
366         put current_date=;
367        run;

current_date=April 10, 2026
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds
      

368        
369        
370        ods html5 (id=saspy_internal) close;ods listing;
371        
The SAS System

372
In [19]:
options nocenter nodate nonumber nosymbolgen;
%let dsn = SASHELP.CLASS;
%let current_date = %sysfunc(date(), worddate.);
%let formatted_date = %sysfunc(putn(%sysfunc(today()), yymmdd10.));
%let HowMany = 5;

%put &current_date;
%put &=formatted_date;
%put &=HowMany;
%put _user_;

proc means data=&dsn; 
run;
title "Data Set: &dsn";
footnote "Created &current_date, &systime";
footnote2 "on the &sysscp, System using SAS Release &sysver";
footnote3 "File name: Ex1_Macrovars_&formatted_date..sas";
proc print data=&dsn (obs = &HowMany); 
run;
SAS Output

Data Set: SASHELP.CLASS

The MEANS Procedure

Variable N Mean Std Dev Minimum Maximum
Age
Height
Weight
19
19
19
13.3157895
62.3368421
100.0263158
1.4926722
5.1270752
22.7739335
11.0000000
51.3000000
50.5000000
16.0000000
72.0000000
150.0000000

Created April 10, 2026, 11:59

on the WIN, System using SAS Release 9.4

File name: Ex1_Macrovars_2026-04-10.sas

Data Set: SASHELP.CLASS

Obs Name Sex Age Height Weight
1 Alfred M 14 69.0 112.5
2 Alice F 13 56.5 84.0
3 Barbara F 13 65.3 98.0
4 Carol F 14 62.8 102.5
5 Henry M 14 63.5 102.5

Created April 10, 2026, 11:59

on the WIN, System using SAS Release 9.4

File name: Ex1_Macrovars_2026-04-10.sas

Note: In the above code, the %LET statement is used in open code (i.e., outside a macro definition) creates a macro variable (Global in scopre) that is available for use anywhere in your SAS code during the SAS session in which the variable was created.

A macro variable can store text up to 65k characters.

Code Explanation¶

The above code snippet includes both macro language and SAS language statements. The macro processor executes macro language statements and then generates SAS code before any SAS language statements are executed.

  • %LET ia a macro statement.

  • &dsn, &HowMany, and &name are macro variable references.

  • When the %LET statement is executed, the text values of the macro variable is stored in the global symbol table.

  • The macro trigger is passed to the macro processor to search the symbol table for the reference. The macro processor resolves the macro variable references (e.g., &dsn and &HowMany) substituting their respective values (sashelp.class, and 5, respectively), passing the resolved value to the Input Stack.

  • %SYSFUNC enables you to invoke a SAS function when constructing macro variables. INPUT and PUT functions are not available with %SYSFUNC and %QSYSFUNC. You must use INPUTN, INPUTC, PUTN, and PUTC instead.

See here more about %SYSFUNC.

  • %PUT _user_; is used to display the names and values all users-defined macro variables.

  • SYMBOLGEN displays the results of resolving macro variable references in SAS log. This option is useful for debugging.

Understandung the use of PUT vs. %PUT statement¶

In [2]:
*Ex3_putlog_PercentPut.sas;
options nodate nosource notes nonumber nocenter 
        leftmargin=0.5in symbolgen;
ods html close;
%LET Path=C:\users\pmuhuri\SASCourse\Week9;
LIBNAME perma "&Path";
data perma.stocks; 
 set sashelp.stocks END=last;
  count+1;
  if last then put
     @5 "Note: Number of observations=" count;
 run;
/*old way to display the macro-variable-value */  
 %put Note: Macro Variable Path = &Path; 

 /*new way to display the macro-variable-value */
 %put Note: Macro variable &=Path;

The SAS System

NOTE: Writing HTML5(SASPY_INTERNAL) Body file: _TOMODS1
SYMBOLGEN:  Macro variable PATH resolves to C:\users\pmuhuri\SASCourse\Week9
NOTE: Libref PERMA was successfully assigned as follows: 
      Engine:        V9 
      Physical Name: C:\users\pmuhuri\SASCourse\Week9

    Note: Number of observations=699
NOTE: There were 699 observations read from the data set SASHELP.STOCKS.
NOTE: The data set PERMA.STOCKS has 699 observations and 9 variables.
NOTE: DATA statement used (Total process time):
      real time           0.02 seconds
      cpu time            0.01 seconds
      

SYMBOLGEN:  Macro variable PATH resolves to C:\users\pmuhuri\SASCourse\Week9
Note: Macro Variable Path = C:\users\pmuhuri\SASCourse\Week9
SYMBOLGEN:  Macro variable PATH resolves to C:\users\pmuhuri\SASCourse\Week9
Note: Macro variable PATH=C:\users\pmuhuri\SASCourse\Week9

The SAS System

E3969440A681A2408885998500000004

SAS Documentation

Macro variables defined by macro programmers are called user-defined macro variables. Those defined by the macro processor are called automatic macro variables. You can define and use macro variables anywhere in SAS programs, except within data lines.

When a macro variable is defined, the macro processor adds it to one of the program's macro variable symbol tables. The variable is held in the global symbol table, which the macro processor creates at the beginning of a SAS session when the following occurs:

* a macro variable is defined in a statement that is outside a macro definition (called open code)

* the variable is created automatically by the macro processor (except SYSPBUFF)
In [1]:
from IPython.display import Image
Image("C:/Data/Percent_put.png")
Out[1]:
No description has been provided for this image
When macro variables are resolved, the leading and trailing blanks from their values are removed.¶
In [5]:
*Ex2_percent_let.sas;
options nonotes nodate nonumber nosource;
ods html close;
%LET CITY1 =   Washington DC ;
%put &=CITY1;
title;

The SAS System

96         ods listing close;ods html5 (id=saspy_internal) file=_tomods1 options(bitmap_mode='inline') device=svg style=HTMLBlue;
96       ! ods graphics on / outputfmt=png;
NOTE: Writing HTML5(SASPY_INTERNAL) Body file: _TOMODS1
97         
98         *Ex2_percent_let.sas;
99         options nonotes nodate nonumber nosource;
SYMBOLGEN:  Macro variable CITY1 resolves to Washington DC
CITY1=Washington DC

The SAS System

E3969440A681A2408885998500000006
Quotation marks are part of the macro variable value.¶
In [6]:
%LET CITY2 =  "Washington DC";
%put &=CITY2;

The SAS System

SYMBOLGEN:  Macro variable CITY2 resolves to "Washington DC"
CITY2="Washington DC"

The SAS System

E3969440A681A2408885998500000007
When macro variables are resolved, embedded extra blanks from their values are not removed.¶
In [16]:
%LET CITY3=   Washington   DC;
%put &=CITY3;
Out[16]:

The SAS System

CITY3=Washington   DC
E3969440A681A2408885998500000019
Mathematical expressions in macro variable values do not get evaluated.¶
In [24]:
%LET m_sum=2+2;
%put &=m_sum;
Out[24]:

The SAS System

M_SUM=2+2
E3969440A681A2408885998500000027
With the %EVAL function, mathematical expressions get evaluated.¶
In [25]:
%LET msum_eval=%eval(2+2);
%put &=msum_eval;
Out[25]:

The SAS System

MSUM_EVAL=4
E3969440A681A2408885998500000028
Only with the %SYSEVALF function, expressions with fractional numbers get evaluated.¶
In [3]:
%LET CALC_FRAC=%SYSEVALF(5.5/2);
%put &=CALC_FRAC;
Out[3]:

The SAS System

SYMBOLGEN:  Macro variable CALC_FRAC resolves to 2.75
CALC_FRAC=2.75
E3969440A681A2408885998500000006
%SYSFUNC is a function that executes SAS functions. PUTN assigns the value based on the value in the first argument and the format in the second argument.¶
In [3]:
%LET amount=%sysfunc(putn(5000000, dollar10.));
%put &=amount;

                                                           The SAS System

AMOUNT=$5,000,000

                                                           The SAS System

E3969440A681A2408885998500000005
In [2]:
options nodate nonumber nonotes nosource;
ods html close;
data _NULL_;
amount = put(5000000, dollar10.);
put amount=
run;

                                                           The SAS System

amount=$5,000,000 .

                                                           The SAS System

E3969440A681A2408885998500000004
In [13]:
%showLog


The SAS System

SYMBOLGEN:  Macro variable NAME_QZ resolves to ('Q', 'Z')
E3969440A681A2408885998500000013
In [3]:
*Ex6_Join_macro_var_text.sas (Part 5);
*Display GLOBAL macro variables;
%put _GLOBAL_;

*Delete user-defined macro variables;
%symdel Path Libref /nowarn;

* and check all macro variables deleted;
%put _GLOBAL_;

The SAS System

NOTE: Writing HTML5(SASPY_INTERNAL) Body file: _TOMODS1
GLOBAL PATH C:\users\pmuhuri\SASCourse\Week9

The SAS System

E3969440A681A2408885998500000005
Find the total number of observations from a SAS data set using SAS macro functions¶
In [9]:
%let dsn=sashelp.class;
%let dsid    = %sysfunc(open(&dsn,i));
%let nobs    = %sysfunc(attrn(&dsid,nlobs));
%let dsclose = %sysfunc(close(&dsid));
%put &=nobs;

The SAS System

SYMBOLGEN:  Macro variable DSN resolves to sashelp.class
SYMBOLGEN:  Macro variable DSID resolves to 1
SYMBOLGEN:  Macro variable DSID resolves to 1
SYMBOLGEN:  Macro variable NOBS resolves to 19
NOBS=19

The SAS System

E3969440A681A2408885998500000010
Readings¶

Slaughter, SJ, and LD. Delwiche. SAS (R) Macro Programming for Beginners, SUGI

In [ ]: