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Proc FCMP – Data Step Functions

Proc FCMP – Data Step Functions. Denise.Poll@sas.com. What is Proc FCMP?. “SAS Function Compiler” Build functions using DATA step syntax Store the functions in a data set Call the functions from the DATA step just as you would any other SAS function

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Proc FCMP – Data Step Functions

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  1. Proc FCMP – Data Step Functions Denise.Poll@sas.com

  2. What is Proc FCMP? • “SAS Function Compiler” • Build functions using DATA step syntax • Store the functions in a data set • Call the functions from the DATA step just as you would any other SAS function • Lots more capabilities, just not covered today

  3. Proc FCMP - History • Prior to Version 9.2 – Limited to Product Procs • SAS/STAT • SAS/ETS • SAS/OR • Post 9.2 available – Data step syntax

  4. Advantages of Writing Your Own Functions • Function makes a program easier to read, write and modify • Reuse and quality control • Test once use many times • Program/function independence

  5. Syntax to Create a Function - 3 level name Proc FCMP outlib = << Ids where to store sasuser.MySubs.MathFncs; << DS and package function day_date( indate, type $); if type = "DAYS" then wkday = weekday(indate); if type = "YEARS" then wkday = weekday(indate*365); return(wkday); endsub; run;

  6. Outlib – 3 Level Name - Package Proc FCMP outlib = sasuser.MySubs.MathFncs; • Library • Dataset • Package – collection of related functions • Could be by organized by application or by corporate department

  7. Pieces and Parts • 4 parts between FUNCTION statement ENDSUB keyword • Function name • day_date • One or more parameters • ( indate, type $); • A body of code • A RETURN statement • return(wkday);

  8. Syntax to Create a Function – Statement & Name Proc FCMP outlib = sasuser.MySubs.MathFncs; functionday_date( indate, type $); << stmt & name if type = "DAYS" then wkday = weekday(indate); if type = "YEARS" then wkday = weekday(indate*365); return(wkday); endsub; run;

  9. Syntax to Create a Function – Naming functionday_date( indate, type $); << stmt & name • Cannot have a function name that collides with a built-in SAS function name. An error message is generated if an attempt is made. • Name must be unique in the package • 2 packages with the same name – qualify name when calling • MathFncs.day_date

  10. Syntax to Create a Function - Arguments function day_date( indate, type $); << arguments function coffee_deal() $ ; << no argument Can have one or more arguments for a function. Specify character arguments by placing a dollar sign ($) after the argument name. In the above example: indateisnumeric and type is a character argument

  11. Syntax to Create a Function – Logic The DAY_DATE function converts a date to a numeric day of the week if type = "DAYS" then wkday = weekday(indate); if type = "YEARS" then wkday = weekday(indate*365);

  12. Usage of SAS Function - weekday Proc FCMP outlib = sasuser.MySubs.MathFncs; function day_date( indate, type $); if type = "DAYS" then wkday = weekday(indate); if type = "YEARS" then wkday = weekday(indate*365); return(wkday); endsub; run;

  13. Syntax to Create a Function – Return Proc FCMP outlib = sasuser.MySubs.MathFncs; function day_date( indate, type $); if type = "DAYS" then wkday = weekday(indate); if type = "YEARS" then wkday = weekday(indate*365); return(wkday); <<Returns a numeric value endsub; run;

  14. Calling the Function Options cmplib = sasuser.mysubs; Data work.usefunc; Numdays = day_date(‘13sep2011’d,”DAYS”); Put numdays=; run; Numdays = 3

  15. Options CMPLIB = Options cmplib = sasuser.mysubs; CMPLIB is a SAS option that supports usage with INSERT and APPEND Options insert=(cmplib=sasuser.meFirst) ; Options append=(cmplib=sasuser.meLast);

  16. Nesting and Scope

  17. Nesting and Scope DATA Step funA funB

  18. Scope – Independent “x” Variable function funB(value); x = value * 100; put 'In funB:' x=; return (x); endsub; function funA(value); x = value; put 'In funA:' x=; y = funB(x); return (y*10); endsub; data _null_; x = funA(5); put 'In DATA Step: ' x=; run;

  19. Scope – Usage data _null_; x = funA(5); put 'In DATA Step:‘ x=; run; Output to the SAS Log: • In funA: x=5 • In funB: x=500 • In DATA Step: x=5000

  20. Function Management • Protecting Functions • Listing the Source • Adding a Function • Removing a Function • Replacing a Function

  21. Protecting Functions • Operating System File Permissions • Unix: chmod • Windows: attrib • z/OS: RACF • libname perm "\\shared\perm" access=readonly; • SAS/Share Read-Only Library

  22. Listing the Function Source proc fcmp outlib=sasuser.funcs.trial; listfunc study_day;

  23. Adding a Function proc fcmp outlib=sasuser.funcs.trial; function study_day(start, event); n = event – start; if n >= 0 then n = n + 1; return(n); endsub;

  24. Removing a Function proc fcmp outlib=sasuser.funcs.trial; deletefunc study_day;

  25. Replacing a Function proc fcmp outlib=sasuser.funcs.trial; deletefunc study_day; function study_day(start, event); ...

  26. Replacing a Function

  27. Proc FCMP - Data Step Statements Not Supported • Data • Set • Merge • Update • Modify • Input • Infile (thru functions OPEN-FETCH, …)

  28. Proc FCMP – Power of Put • Use Put for debugging Results of a Put statement can go to the PRINT (default) and LOG destinations … FILE log; Put variable ;

  29. Acknowledgements and Questions • Thanks to GASUG for the invitation to present! • Thanks to Jason Secosky who provided a subset of the material for this presentation

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