When best to use the %let statement, the symput routine, or the into clause to create macro variables

When Best to Use the %LET Statement, the SYMPUT Routine, or the INTO Clause to Create Macro Variables

Arthur LiDepartment of Information Science

City of Hope Comprehensive Cancer Center Duarte, CA

DATA Step PROC Steps

SAS Macro Facility

BASE SAS

INTRODUCTION

Use to generate SAS codes

more…

PROC SQL


SAS Macro Facility

BASE SAS

INTRODUCTION

more…

PROC SQL

SAS Macro Facility -Has its own language

SAS MacroVariables

SAS Macro Programs

Prerequisites:

Focus of this talk


SAS Macro Facility

BASE SAS

INTRODUCTION

more…

PROC SQL

SAS Macro Facility -Has its own language

SAS MacroVariables

SAS Macro Programs

Prerequisites:

SAS MacroVariables

SAS Macro Variables

AutomaticUser-

Defined

Focus of this talk

THE %LET STATEMENT

One way to create a macro variable is to use the %LET statement

%LET MACRO-VARIABLE = VALUE;

%let var1 = 4 + 3;

The VALUE is stored as character strings

MACRO-VARIABLE var1

VALUE 4 + 3

Mathematical expressions are not evaluated

THE %LET STATEMENT



%let var2 = leading blank;


MACRO-VARIABLE var2

VALUE leading blank

Leading and trailing blanks are removed

THE %LET STATEMENT



%let var3 = " quotations ";


MACRO-VARIABLE var3

VALUE “ quotations ”

Quotation marks are part of the values

THE %LET STATEMENT



If MACRO-VARIABLE and/or VALUE contain references to another macro variable, the reference will be evaluated first before the assignment

REFERENCING MACRO VARIABLES

Once a macro variable is defined, the value of the macro variable is stored in the global symbol table

%let ht = 63;

Global Symbol Table

SAS Automatic Macro Variables:

SYSDATE 19JUN06

SYSDAY Monday

SYSTIME 10:34

…

…

User-Defined Macro Variables:ht 63

REFERENCING MACRO VARIABLES

To substitute a macro variable in the SAS program, you must reference the macro variable:

%let ht = 63;data ex1; set height; tall = height > &ht;run;

Global Symbol Table

SAS Automatic Macro Variables:

SYSDATE 19JUN06

SYSDAY Monday

SYSTIME 10:34

…

…

User-Defined Macro Variables:ht 63

& MACRO-VARIABLE

63

If the reference of a macro variable is within quotations, the double quotation marks must be used

“& MACRO-VARIABLE”

UNDERSTANDING SAS PROCESSING

In order to understand how macro variables are processed and stored, one needs to understand how SAS processing works

Compilation phaseEach statement is scanned for syntax

errors

Execution phaseThe DATA step reads

and processes the input data

the descriptor portion is created

If there is no syntax error

Done in the compiler

How are the SAS statements transferred to the compiler?

A DATA step is processed in sequence in two phases


INPUT STACK When a program is submitted, all the codes are placed in a memory area, called the input stack

data ex1; set height; tall = height > 63;run;

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKdata ex1; set height; tall = height > 63;run;

The word scanner takes the statements from the input stack and tokenizes the statements into tokens

The word scanner then directs the tokens to the right location

DATA step compiler Macro processor, etc.


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKex1; set height; tall = height > 63;run;

data


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; set height; tall = height > 63;run;

ex1

data


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKset height; tall = height > 63;run;

;

ex1 data


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKheight; tall = height > 63;run;

set

; ex1

data


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; tall = height > 63;run;

height

set ;

data ex1


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKtall = height > 63;run;

;

height set

data ex1;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK= height > 63;run;

tall

; height

data ex1; set


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKheight > 63;run; =

tall ;

data ex1; setheight


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK> 63;run; height

= tall

data ex1; setheight;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK63;run; >

height =

data ex1; setheight; tall


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK;run; 63

> height

data ex1; setheight; tall =


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKrun;

;

63 >

data ex1; setheight; tall =height


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK;

run

; 63

data ex1; setheight; tall =height >


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

;

run ;

data ex1; setheight; tall =height > 63


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

; run

data ex1; setheight; tall =height > 63;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

;

data ex1; setheight; tall =height > 63; run


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

data ex1; setheight; tall =height > 63; run;

When the compiler receives the semicolon following the RUN statement, it stops taking tokens from the word scanner


Compilation phaseEach statement is

scanned for syntax errors.

Execution phaseThe DATA step reads and processes the input data.

If there is no syntax error


Types of Token Contains … Examples

Literal Characters enclosed in quotation marks “John” ‘John’

Numerals including decimals, E-notation, date, time, datetime constants, and hexadecimal constants

555‘01mar2010’d30e4

Number

Characters that begin with a letter or underscore and that continues with underscores, letters, or numbers. A period can sometimes be part of a name

_n_meansdollar9.2Descending

Name

Characters other than a letter, number, or underscore that have a special meaning to the SAS system

Special character

/ + % & . ;

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK%let ht =63; data ex1; set height; tall =height >&ht; run;

The macro facility includes a macro processor that is responsible for processing all macro language elements

MACRO PROCESSOR

Macro variable references and %LET statements are part of the macro language

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK%let ht =63; data ex1; set height; tall =height >&ht; run;

Macro trigger: %LET name-token & name-token

MACRO PROCESSOR

The word scanner needs to recognize the macro language and direct them to the macro processor

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKlet ht =63; data ex1; set height; tall =height >&ht; run;

%

MACRO PROCESSOR

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKht =63; data ex1; set height; tall =height >&ht; run;

let

%

MACRO PROCESSORWhen the word

scanner detects %LET (a macro trigger), it starts to direct the tokens to the macro processor

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK=63; data ex1; set height; tall =height >&ht; run;

ht

let

MACRO PROCESSOR

%

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK63; data ex1; set height; tall =height >&ht; run;

=

ht

MACRO PROCESSOR GLOBAL SYMBOL TABLE

SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34...User-Defined Macro Variables

let

%

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKdata ex1; set height; tall =height >&ht; run;

;

63


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34...User-Defined Macro Variables

=

ht

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKex1; set height; tall =height >&ht; run;

data

;


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34...User-Defined Macro Variables ht

63

=

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; set height; tall =height >&ht; run;

ex1

data


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34...User-Defined Macro Variables ht

;

63

The macro processor stops processing the tokens when the semicolon is encountered

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKset height; tall =height >&ht; run;

;

ex1 data


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34...User-Defined Macro Variables ht 63

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKheight; tall =height >&ht; run;

set

; ex1



data

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; tall =height >&ht; run;

height

set ;



data ex1

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKtall =height >&ht; run; ;

height set



data ex1;

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK=height >&ht; run; tall

; height



data ex1; set

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKheight >&ht; run; =

tall ;



data ex1; setheight

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK>&ht; run;

height

= tall



data ex1; setHeight;

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK&ht; run;

>

height =



data ex1; setheight; tall

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKht; run;

&

> height



data ex1; setheight; tall =

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;

ht

& >



data ex1; setheight; tall =height

When the word scanner encounters the ampersand followed by HT, it directs them to the macro processor

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;

ht



&

data ex1; setheight; tall =Height >

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;



ht


MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;



ht


The macro processor looks up the macro variable HT and takes its value from the symbol take

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;



ht


63

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;




63

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK63; run;




MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK; run;

63




MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACKrun;

;

63




MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK;

run

; 63




MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

;

run ;



data ex1; setheight; tall =Height > 63

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

; run



data ex1; setheight; tall =Height > 63;

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK

;



data ex1; setheight; tall =Height > 63; run

MACRO PROCESSING

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILER

INPUT STACK



data ex1; setheight; tall =Height > 63; run;

MACRO PROCESSING

PROCESSING MACRO VARIABLES AT EXECUTION TIME

In many applications, we need to create macro variables during DATA step execution

For example, we might need to create macro variables and assign values to them based on

data values in SAS data sets or in external filesprogramming logiccomputed values


name sex height tall

1 John m 65 1

2 Tom m 60 0

3 Mary f 62 0

4 Helen f 64 1

Create macro variable TITL - serves as a title for printing the dataset ex1

If there are some students > 63 inches (when tall = 1), TITL = “Some students are taller than 63 inches” If none of the students > than 63 inches, TITL = “None of the students are taller than 63 inches”

Ex1:



1 John m 65 1

2 Tom m 60 0

3 Mary f 62 0

4 Helen f 64 1

Ex1:

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do; %let titl = "Some students are taller than 63 inches"; end; else do; %let titl = "None of the students are taller than 63 inches"; end; end;run;



1 John m 65 1

2 Tom m 60 0

3 Mary f 62 0

4 Helen f 64 1

Ex1:

proc print data=ex1; title &titl;run;

None of the students are taller than 63 inches

Obs name sex height tall 1 John m 65 1 2 Tom m 60 0 3 Mary f 62 0 4 Helen f 64 1

WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do; %let titl ="Some students are taller than 63 inches"; end; else do; %let titl = "None of the students are taller than 63 inches"; end; end; run;


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34..User-Defined Macro Variables


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

="Some students are taller than 63 inches"; end; else do; %let titl = "None of the students are taller than 63 inches"; end; end; run;

titl

let


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34..User-Defined Macro Variables

%

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

%let titl = "None of the students are taller than 63 inches"; end; end; run;

;

do else


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34..User-Defined Macro Variables Titl Some students are taller than 63 inches

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

let titl = "None of the students are taller than 63 inches"; end; end; run;

%

; do



data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end; else


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

= "None of the students are taller than 63 inches"; end; end; run;

titl

let



%

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end; else do;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

titl = "None of the students are taller than 63 inches"; end; end; run;

let

% ;



data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end; else do


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK

end; run;;

end


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34..User-Defined Macro Variables Titl None of the students are taller than 63 inches

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end; else do;


WORD SCANNER

TOKENNIZERDETERMINE

DESTINATION

COMPILERINPUT STACK


SAS Automatic Macro VariablesSYSDATE 19JUN06SYSDAT MondaySYSTIME 10:34..User-Defined Macro Variables Titl None of the students are taller than 63 inches

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do;end; else do; end; end; run;




1 John m 65 1

2 Tom m 60 0

3 Mary f 62 0

4 Helen f 64 1

Ex1:

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do; %let titl = "Some students are taller than 63 inches"; end; else do; %let titl = "None of the students are taller than 63 inches"; end; end;run;

Here is what the program will look like when it is processed by the compiler

THE SYMPUT ROUTINE

To create a macro variable during the DATA step execution, use the SYMPUT routine

CALL SYMPUT (MACRO-VARIABLE, VALUE);

Both MACRO-VARIABLE and VALUE can be specified as

literal (text in quotations) a DATA step variable a DATA step expression

THE SYMPUT ROUTINE


Both arguments are literals

‘MACRO-VARIABLE’:Text enclosed in the quotation marks is the exact macro variable name

‘VALUE’:The exact value that is assigned to the MACRO-VARIABLE

THE SYMPUT ROUTINE

data _null_; set ex1 end=last; if tall then count_tall +1; if last then do; if count_tall then do; call symput('titl', 'Some students are taller than 63 inches'); end; else do; call symput('titl', 'None of the students are taller than 63 inches'); end; end;run;

Use the SUMPUT routine to fix the previous program

THE SYMPUT ROUTINE

proc print data=ex1; title &titl;run;

Some students are taller than 63 inches

Obs name sex height tall 1 John m 65 1 2 Tom m 60 0 3 Mary f 62 0 4 Helen f 64 1

THE SYMPUT ROUTINE


When VALUE is a DATA step variable

A DATA step variable; not in quotation marks

You are assigning the value of a DATA step variable to the MACRO-VARIABLE

Any leading or trailing blanks that are part of the values of a DATA step variable will be part of the macro variables

For a numeric variable, the values will be converted to character variables by using the BEST12. format

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Suppose that you would like to create four macro variables:

Height:

Macro Variable Names Values

John_ht 65

Tom_ht 60

Mary_ht 62

Helen_ht 64

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

data _null_; set height; if name = 'John' then call symput ('John_ht', height); else if name = 'Tom' then call symput ('Tom_ht', height); else if name = 'Mary' then call symput ('Mary_ht', height); else if name = 'Helen' then call symput ('Helen_ht', height);run;

Height:

HEIGHT is not in quotation marks

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

%put macro variable John_ht: &John_ht;%put macro variable Tom_ht: &Tom_ht;%put macro variable Mary_ht: &Mary_ht;%put macro variable Helen_ht: &Helen_ht;

Height:

359 %put macro variable John_ht: &John_ht;macro variable John_ht: 65360 %put macro variable Tom_ht: &Tom_ht;macro variable Tom_ht: 60361 %put macro variable Mary_ht: &Mary_ht;macro variable Mary_ht: 62362 %put macro variable Helen_ht: &Helen_ht;macro variable Helen_ht: 64

Log:

THE SYMPUT ROUTINE


When MACRO-VARIABLE is a DATA step variable

A DATA step variable; not in quotation marks

You are creating multiple macro variables The names of the macro variables are the values of a

DATA step variable

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64


Height:


John 65

Tom 60

Mary 62

Helen 64

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Height:

data _null_; set height; call symput (name, height);run;

NAME is not in quotation marks

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Height:

%put macro variable John: &John;%put macro variable Tom: &Tom;%put macro variable Mary: &Mary;%put macro variable Helen: &Helen;

368 %put macro variable John: &John;macro variable John: 65369 %put macro variable Tom: &Tom;macro variable Tom: 60370 %put macro variable Mary: &Mary;macro variable Mary: 62371 %put macro variable Helen: &Helen;macro variable Helen: 64

Log:

Notice that “blanks” are part of the macro variables

THE SYMPUT ROUTINE


DATA step expressions can be used in one/both arguments

A DATA step expression

A DATA step expression

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64


Height:


height_John 65

height_Tom 60

height_Mary 62

height_Helen 64

Also, remove the leading blanks

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Height:

data _null_; set height; call symput ("height_" ||name, trim(left(height)));run;

THE SYMPUT ROUTINE

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Height:

%put macro variable height_John: &height_John;%put macro variable height_Tom: &height_Tom;%put macro variable height_Mary: &height_Mary;%put macro variable height_Helen: &height_Helen;

411 %put macro variable height_John: &height_John;macro variable height_John: 65412 %put macro variable height_Tom: &height_Tom;macro variable height_Tom: 60413 %put macro variable height_Mary: &height_Mary;macro variable height_Mary: 62414 %put macro variable height_Helen: &height_Helen;macro variable height_Helen: 64

Log:

THE SYMPUTX ROUTINE

The SYMPUTX routine is an improved version of the SYMPUT routine

The SYMPUTX routine can remove leading and trailing blanks from both arguments

For example, the previous program can be re-written as below:

data _null_; set height; call symputx ("height_" ||name, height);run;

THE SYMPUTX ROUTINE

%put macro variable height_John: &height_John;%put macro variable height_Tom: &height_Tom;%put macro variable height_Mary: &height_Mary;%put macro variable height_Helen: &height_Helen;

429 %put macro variable height_John: &height_John;macro variable height_John: 65430 %put macro variable height_Tom: &height_Tom;macro variable height_Tom: 60431 %put macro variable height_Mary: &height_Mary;macro variable height_Mary: 62432 %put macro variable height_Helen: &height_Helen;macro variable height_Helen: 64

Log:

THE SYMPUTX ROUTINE

Difference between CALL SYMPUTX and CALL SYMPUT

CALL SYMPUTX CALL SYMPUT

Does not write a note to the SAS log when the 2nd argument is numeric

Writes a note to the SAS log when the 2nd argument is numeric

Uses a field width of up to 32 characters for converting a numeric 2nd argument to characters

Uses a field width of up to 12 characters for converting a numeric 2nd argument to characters

Left-justifies both arguments and trims trailing blanks

Does not left-justify the arguments and trims trailing blanks from the first argument only

Enables you to specify the symbol table

Does not enable you to specify the symbol table

PROCESSING MACRO VARIABLES DURING THE EXECUTION OF PROC SQL

You can create/update macro variables during the execution of PROC SQL

The INTO clause in the SELECT statement performs a similar role to the SYMPUT(X) routine in the DATA step

The INTO clausecan create one or more macro variables can assign a calculated result or the value of a data

variable to a macro variablecan only be used in the outer query of a SELECT

statement cannot be used when you are creating a table or a

view


Here is the general syntax for PROC SQL and the INTO clause:

PROC SQL <PRINT|NOPRINT>;SELECT column1 <, column2, …>INTO :macro-variable1 <, :macro-variable2, …>FROM table |view<other clauses>; QUIT;

To select one or more columns from SQL table/view, you can specify column1, column2, … after the keyword SELECT




Macro-variable1, macro-variable2 are the names of the macro variables that you are creating




You must write colon(s) (:) before each of the macro variables




The INTO clause does not trim the leading and trailing blanks of the macro variables




To suppress display-output from PROC SQL, you can use the NOPRINT option


You can assign a calculated summary statistic to a macro variable

Suppose you would like to create a macro variable MEAN_HT - average heights of students

proc sql noprint; select mean(height) into: mean_ht from height;quit;

%put macro variable mean_ht: &mean_ht;

523 %put macro variable mean_ht: &mean_ht;macro variable mean_ht: 62.75Log:


Without using the PROC SQL, you must use multiple steps to accomplish this task

proc means data=height noprint; var height; output out=height_mean mean=ht_mean;run;

data _null_; set height_mean; call symputx('mean_ht1', ht_mean);run;


In the previous program, we created four macro variables:data _null_; set height; if name = 'John' then call symput ('John_ht', height); else if name = 'Tom' then call symput ('Tom_ht', height); else if name = 'Mary' then call symput ('Mary_ht', height); else if name = 'Helen' then call symput ('Helen_ht', height);run;

We can use PROC SQL to achive the same taskproc sql noprint; select height into: John_ht1 from height where name = 'John'; select height into: Tom_ht1 from height where name = 'Tom'; select height into: Mary_ht1 from height where name = 'Mary'; select height into: Helen_ht1 from height where name = 'Helen';quit;


You can create a range of macro variablesEach of the macro variables will contain each row in the

result of the SELECT statement

PROC SQL <PRINT|NOPRINT>;SELECT column1 <, column2, …>INTO :macro-variable1_1 - :macro-variable1_n < NOTRIM> <, :macro-variable2_1 - :macro-variable2_n < NOTRIM>, …>FROM table |view<other clauses>; QUIT;



name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

name1name2name3name4

height1height2height3height4

into :name1 - :name4, :height1 - :height4



By default, the leading and trailing blanks are removed from values before they are stored in macro variables

If you don’t want to remove the leading and trailing blanks, you can use the NOTRIM option


Suppose that you would like to create macro variables NAME1 – NAME4 and HEIGHT1 – HEIGHT4 to store these four students’ names and their heightsproc sql noprint; select name, height into :name1 - :name4,

:height1 - :height4 from height;quit;

%put macro variable name1: &name1;%put macro variable name2: &name2;%put macro variable name3: &name3;%put macro variable name4: &name4;%put macro variable height1: &height1;%put macro variable height2: &height2;%put macro variable height3: &height3;%put macro variable height4: &height4;


Suppose that you would like to create macro variables NAME1 – NAME4 and HEIGHT1 – HEIGHT4 to store these four students’ names and their heights663 %put macro variable name1: &name1;macro variable name1: John664 %put macro variable name2: &name2;macro variable name2: Tom665 %put macro variable name3: &name3;macro variable name3: Mary666 %put macro variable name4: &name4;macro variable name4: Helen667 %put macro variable height1: &height1;macro variable height1: 65668 %put macro variable height2: &height2;macro variable height2: 60669 %put macro variable height3: &height3;macro variable height3: 62670 %put macro variable height4: &height4;macro variable height4: 64


When creating a range of macro variables, PROC SQL restricts the name convention for the macro variables

The names of the macro variables must end with an integer with a valid range, such as HEIGHT1 – HEIGHT4

You won’t be able to use more meaningful names such as JOHN_HT, TOM_HT, MARY_HT, and HELEN_HT


You can use the INTO clause to create a macro variable that holds all the values of a column by concatenating them and separating them by a delimiter

PROC SQL <PRINT|NOPRINT>;SELECT column1 <, column2, …> INTO :macro-variable1 SEPARATED BY ‘delimiter1’ <, :macro-variable2 SEPARATED BY ‘delimiter2’, …>FROM table |view<other clauses>; QUIT;

Delimiter1 is used to separate all the values in the column and must be enclosed in quotation marks


Create macro variables

name sex height

1 John m 65

2 Tom m 60

3 Mary f 62

4 Helen f 64

Macro Variable Value

NAMELIST John Tom Mary Helen

HEIGHTLIST 65,60,62,64


proc sql noprint; select name, height

into : namelist separated by ' ', : heightlist separated by ','

from height;quit;

%put macro variable namelist: &namelist;%put macro variable heightlist: &heightlist;

871 %put macro variable namelist: &namelist;macro variable namelist: John Tom Mary Helen872 %put macro variable heightlist: &heightlist;macro variable heightlist: 65,60,62,64

CONCLUSION

Creating a macro variable by using the %LET statement occurs before the execution of any other SAS language statements

To create a macro variable during the DATA step execution, you must use either the SYMPUT or SYMPUTX routines

To create a macro variable during the execution of PROC SQL, you must use the INTO clause

Understanding the mechanisms of creating macro variables is an important foundation for learning how best to write macro programs

REFERENCES

Burlew, Michele M. SAS® Macro Programming Made Easy, 2nd Edition.

SAS Online Doc® 9.1.3. Cary, NC: SAS Institute Inc.

ACKNOWLEDGEMENT

I would like to thank Kathryn McLawhorn and Scott McElroy, Technical Support Analysts from SAS Technical Support, for their valuable programming suggestions and insight

CONTACT INFORMATION

Arthur Li

City of Hope

Division of Information Science

1500 East Duarte Road

Duarte, CA 91010 - 3000

Phone: (626) 256-4673 ext. 65121

E-mail: [email protected]

Education

When best to use the %let statement, the symput routine, or the into clause to create macro variables