STS Customer Insight in Marketing January 2003

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Programming Techniques in SAS Using the Macro
Facility
Programming Techniques in SAS Using the Macro
Facility















































JC Raymond, Education, SAS
Bill Fehlner, Education, SAS 514
395-4087 jc.raymond_at_sas.com 416
307-4513 bill.fehlner_at_sas.com
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(No Transcript)
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Programming Examples

• Reuse dynamic code
• Automated Process
• Automate job control
• Extend SQL with custom functions
• Pure macros without data steps
• The Factorial
• Divide and Conquer

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Some Macro Building Blocks

• Macro programs with parameters
• Macro Variables stored in Symbol tables
• Automatic variables, e.g. System return codes
• Run-time functions, e.g. the resolve function.
• Macro Functions
• Recursive programming

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1. Reuse Dynamic Code
demo1_dynamicAutoexec.sas
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1. Reuse Dynamic Code
The Greeting Macro
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1. Reuse Dynamic Code
The Greeting Macro

• sysuserid contains the userid of the SAS session
  
• Keyword parameters have a default value.
• A macro statement begins a macro definition and
  a mend statement ends it.
• put statements write to the SAS log.

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1. Reuse Dynamic Code
Macro Variable Dictionary
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1. Reuse Dynamic Code
Macro Variable Dictionary
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1. Reuse Dynamic Code
Delete Variables
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2. Automated Process
Final report
Process parameters
Sas data sets
Proc tabulate
Create sample data
Sas data set
Task 2
Task 2
Task 1 obs1
Task 1
Task 1
Data step reads log
Sas log
Route log file to disk
Task 2 obs1
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2. Automated Process
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2. Automated Process
Using The Benchmark Macro
demo2_runBenchmark.sas
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2. Automated Process
The Benchmark Macro
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2. Automated Process
Take-aways

• local insures no interference with variables
  potentially existing outside of the macro
  procedure.
• A macro program can check for a null parameter.

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2. Automated Process
The Benchmark Macro
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2. Automated Process
Take-aways

• include allows blocks of code to be stored in
  text files and inserted into the program code at
  any time.
• scan can be used to split a parameter value into
  multiple units.
• Title statements (and any others) can be dynamic
  in the macro world.

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2. Automated Process
The Benchmark Macro
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2. Automated Process
Take-aways

• Proc Printto can route the SAS log to a text
  file.
• Multiple ampersand expressions select one macro
  variable from a named group of macro variables.

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3. Automated Job Control
demo3_demostrateJobControl.sas
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3. Automated Job Control
The Jobcontrol Macro
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3. Automated Job Control
Take-aways

• The parmbuff option permits a variable number of
  parameters in a macro call.
• scan can be used to select a parameter from the
  parameter string stored in the syspbuff macro.
• syspbuff contains the entire parameter string.
  The str((,)) specifies that a right
  parenthesis, a comma, and a left parenthesis are
  delimiters for the scan.
• eval( ) function permits integer arithmetic in a
  macro expression.

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4. Extend SQL
demo4_surrogateKeys.sas
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4. Extend SQL
The Nextval Macro
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4. Extend SQL
Take-aways

• Macro parameters can be passed by reference.
  In this case constantName contains a reference to
  a macro variable
• constantName inserts the name of the target
  macro variable.
• constantName inserts the value of the target
  macro variable.
• constantName appearing outside of a macro
  statement supplies the return value for the
  nextval macro program.

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4. Extend SQL
The Nextval Macro
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4. Extend SQL
Take-aways

• The input( ) function converts its character
  argument to a numeric value.
• The resolve( ) function processes a macro
  expression (in this case the nextval macro
  program) and returns any text produced.
• The argument to the resolve( ) function is in
  single quotes so it does not get processed until
  run time.

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5. Pure Macros
without data steps
demo5_QueryDescriptor.sas
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5. Pure Macros
The obsnvars Macro
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5. Pure Macros
Take-aways

• global and local allow you to determine where
  macro variables are stored.
• sysfunc( ) allows the macro processor to use
  data step functions directly.
• Open( ), attrn( ) and close( ) functions access
  the data set and read attribute values from the
  descriptor.
• sysfunc(sysmsg( ) ) captures error message text.

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6. Recursive Programming
http//www.mantasoft.co.uk/_stuff/Recursive.htm
n!
n! gamma(n1)
demo6_Factorial.sas
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7. Divide Conquer
Not Sorted
Not Sorted
SORT
SORT
Sorted
Sorted
demo7_DivideAndConquer.sas
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7. Divide Conquer
The actual input data
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7. Divide Conquer
demo7_DivideAndConquer.log
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7. Divide Conquer
Take Away

• sysfunc(time(),best15.) allows the macro
  processor to use data step functions directly and
  format the result.
• sysevalf(to - from) performs floating-point
  arithmetic and returns a value that is formatted
  using the BEST32. format.
• sysfunc(putn(sysevalf(to - from),time12.3)).
  sysfunc cannot format the result of the
  sysevalf since it is expecting a function as
  argument reason why we must used putn.

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7. Divide Conquer
PROC SORT TIME -gt 02220.658
SORT MACRO TIME -gt 00921.227
A SAVING OF 01259 (58)
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7. Divide Conquer
The SORT macro
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7. Divide Conquer
Take Away

• macro sort(dsnin,dsnout,by,maxrec) allows
• passing parameters by position

call symput('dsn' trim(left(put(i,3.))), '___'
trim(left(put(i,3.))))

• The macro variables dsn1, dsn2, dsn3 dsnn will
  contain ___1, ___2, ___3 ___n the name of
  the temporary sorted datasets.
• NB_WRK is the number of temporary datasets.
• MAXREC is the maximum number of observation per
  Sort.
• NOBS is the total number of observations to be
  sorted from the input dataset.

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7. Divide Conquer
The SORT macro
1 Dataset having a length of less than MAXREC
Split Dataset into Several Sub-datasets While Sort
ing
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7. Divide Conquer
The SORT macro
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7. Divide Conquer
The SORT macro
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How To Learn More

• Instructor based training
• http//support.sas.com/training/Canada
• Next SAS Macro Language, a two-day course,
  starting on
• February 25th in Montreal
• February 2nd in Ottawa
• December 15th in Toronto
• Next SAS Macro Language Advanced Topics, a
  one-day course on
• March 26th in Montreal
• February 11th in Ottawa and
• February 16th in Toronto

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How To Learn More

• Instructor based training
• http//support.sas.com/training/Canada
• Next SAS Macro Language, a two-day course,
  starting on
• February 25th in Montreal
• February 2nd in Ottawa
• December 15th in Toronto
• Next SAS Macro Language Advanced Topics, a
  one-day course on
• March 26th in Montreal
• February 11th in Ottawa and
• February 16th in Toronto

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How To Learn More

• Technical Support
• http//support.sas.com/techsup/intro.html
• http//support.sas.com/techsup/faq/macro.html

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How To Learn More

• Books
• SAS Guide to Macro Processing 56041
• SAS Macro Language Reference 55501
• SAS Macro Facility Tips Techniques 55097
• Carpenters Complete Guide to the SAS Macro
  Language 56100

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Questions ?