SAS Tips, Tricks And Techniques

SAS Tips, Tricks and TechniquesKirk Paul Lafler, Software Intelligence CorporationAbstractThe base-SAS System offers users the power of a comprehensive DATA step programming language, anassortment of powerful PROCs, a macro language that extends the capabilities of the SAS System, and user-friendlyinterfaces including the SAS Display Manager. This presentation highlights numerous SAS tips, tricks and techniquesusing a collection of proven code examples related to effectively using the SAS Display Manager and its manyfeatures; process DATA step statements to handle subroutines and code libraries; deliver output in a variety offormats ; construct reusable code; troubleshoot and debug code; and an assortment of other topics.IntroductionThis paper illustrates several tips, tricks and techniques related to the usage of the Base-SAS software. We willexamine a variety of topics including SAS System options, DATA step programming techniques , logic conditions,output delivery and ODS, macro programming, and an assortment of other techniques .Example TablesThe data used in all the examples in this paper consists of a selection of movies that I’ve viewed over the years. TheMovies table consists of six columns: title, length, category, year, studio, and rating. Title, category, studio, and ratingare defined as character columns with length and year being defined as numeric columns. The data stored in theMovies table is depicted below.MOVIES TableThe data stored in the ACTORS table consists of three columns: title, actor leading, and actor supporting, all ofwhich are defined as character columns. The data stored in the Actors table is illustrated below.ACTORS Table

Base-SAS Tips, Tricks and TechniquesThis section covers numerous base-SAS software tips , tricks and techniques . Whether you are a SAS expert who iscomfortable with the many features offered in the Base SAS product or someone just getting started, these tips willmake your programming experience a more rewarding one. By taking the time to learn the Base SAS fundamentals —including terminology, library structures, programming concepts, user interface, SAS Explorer, and numerous otheraspects —you will get better results using this powerful product. You will learn about useful features step-by-step tohelp you become a more knowledgeable SAS user.Tip #1 – Writing SAS source files included with a %INCLUDE statement to the SAS LogBy default, SAS source statements included with a %INCLUDE statement are NOT automatically written to the SASLog. To print secondary SAS source statements included with a %INCLUDE statements, users will need to specifythe SOURCE2 system option. The default setting is NOSOURCE2. Either option can be specified in an OPTIONSstatement, in the OPTIONS window, at SAS invocation, or in the configuration file.Tip #2 – Specifying the most recently created data set to use in a read operationBy default, the LAST system option is set to use the most recently created data set. This automatic feature iscommonly found in procedure code when the DATA option is omitted from a PROC. To override this built-in default,the LAST system option can be defined as any valid temporary or permanent SAS data set name (refer to dataset naming conventions). The LAST option can be specified in an OPTIONS statement, in the OPTIONS window,at SAS invocation, or in the configuration file.Tip #3 – Preventing SAS data sets from accidentally being replacedUsers can specify the NOREPLACE system option to prevent a permanent SAS data set from being accidentallyreplaced with another like-named data set. Conversely, by specifying the REPLACE system option like-named datasets can be overwritten. The REPLACE NOREPLACE option can be specified in an OPTIONS statement, in theOPTIONS window, at SAS invocation, or in the configuration file.Tip #4 – Executing Conditional Logic with IF-THEN / ELSEThe IF-THEN / ELSE construct enables a sequence of conditions to be constructed that when executed goes throughthe IF-THEN conditions until it finds one that satisfies the expression. The example shows a variable Movie Lengthbeing assigned a character value of “Short”, “Medium”, or “Long” based on the mutually exclusive conditions specifiedin the IF-THEN and ELSE conditions. Although not required, the ELSE condition is useful to prevent missing valuesfrom being assigned to Movie Length.Code:DATA ATTRIB EXAMPLE;ATTRIB Movie Length LENGTH 7 LABEL ’Movie Length’;SET MOVIES;IF LENGTH 120 THEN Movie Length ‘Short’;ELSE IF LENGTH 160 THEN Movie Length ‘Long’;ELSE Movie Length ‘Medium’;RUN;ResultsThe SAS SystemTitleBrave HeartCasablancaChristmas VacationComing to AmericaDraculaDressed to KillForrest GumpGhostLength17710397116130105142127Movie LengthLongShortShortShortMediumShortMediumMedium

JawsJurassic ParkLethal WeaponMichaelNational Lampoon's VacationPoltergeistRockyScarfaceSilence of the LambsStar WarsThe Hunt for Red OctoberThe TerminatorThe Wizard of iumMediumShortShortLongTip #5 – Executing Conditional Logic with a SELECT statementAs an alternative to a series of IF-THEN/ELSE statements, a SELECT statement with one or more WHEN conditionscan be specified. The SELECT-WHEN statement enables a sequence of conditions to be constructed, that whenexecuted goes through the WHEN conditions until it finds one that satisfies the expression. Typically a sequence ofWHEN conditions are specified for a long series of conditions. The example shows a variable Movie Length beingassigned a character value of “Short”, “Medium”, or “Long” based on the mutually exclusive conditions specified in theWHEN and OTHERWISE conditions. Although not required, the OTHERWISE condition is useful to prevent missingvalues being assigned to Movie Length.Code:DATA SELECT EXAMPLE;SET MOVIES;LENGTH Movie Length 6.;SELECT;WHEN (LENGTH 120) Movie Length ‘Short’;WHEN (LENGTH 160) Movie Length ‘Long’;OTHERWISE Movie Length ‘Medium’;END;RUN;ResultsThe SAS SystemTitleLengthBrave Heart177Casablanca103Christmas Vacation97Coming to America116Dracula130Dressed to Kill105Forrest Gump142Ghost127Jaws125Jurassic Park127Lethal Weapon110Michael106National Lampoon's Vacation98Movie diumMediumShortShortShort

PoltergeistRockyScarfaceSilence of the LambsStar WarsThe Hunt for Red OctoberThe TerminatorThe Wizard of gShortMediumMediumShortShortLongCase LogicIn the SQL procedure, a case expression provides a way of conditionally selecting result values from each row in atable (or view). Similar to an IF-THEN construct, a case expression uses a WHEN-THEN clause to conditionallyprocess some but not all the rows in a table. An optional ELSE expression can be specified to handle an alternativeaction should none of the expression(s) identified in the WHEN condition(s) not be satisfied.A case expression must be a valid SQL expression and conform to syntax rules similar to DATA step SELECTWHEN statements. Even though this topic is best explained by example, let’s take a quick look at the syntax.CASE column-name WHEN when-condition THEN result-expression WHEN when-condition THEN result-expression ELSE result-expression ENDA column-name can optionally be specified as part of the CASE-expression. If present, it is automatically madeavailable to each when-condition. When it is not specified, the column-name must be coded in each when-condition.Let’s examine how a case expression works.If a when-condition is satisfied by a row in a table (or view), then it is considered “true” and the result-expressionfollowing the THEN keyword is processed. The remaining WHEN conditions in the CASE expression are skipped. If awhen-condition is “false”, the next when-condition is evaluated. SQL evaluates each when-condition until a “true”condition is found or in the event all when-conditions are “false”, it then executes the ELSE expression and assignsits value to the CASE expression’s result. A missing value is assigned to a CASE expression when an ELSEexpression is not specified and each when-condition is “false”.Tip #6 – Conditional Execution in SQL with a Case ExpressionIn the following example, we will examine how a case expression actually works. Suppose a value of “Short”,“Medium”, or “Long” is desired for each of the movies. Using the movie’s length (LENGTH) column, a CASEexpression is constructed to assign one of the desired values in a unique column called Movie Length. A value of‘Short’ is assigned to the movies that are shorter than 120 minutes long, ‘Long’ for movies longer than 160 minuteslong, and ‘Medium’ for all other movies. A column heading of Movie Length is assigned to the new derived outputcolumn using the AS keyword.SQL CodePROC SQL;SELECT TITLE,LENGTH,CASEWHEN LENGTH 120 THEN 'Short'WHEN LENGTH 160 THEN 'Long'ELSE 'Medium'END AS Movie LengthFROM MOVIES;QUIT;

ResultsThe SAS SystemTitleLengthBrave Heart177Casablanca103Christmas Vacation97Coming to America116Dracula130Dressed to Kill105Forrest Gump142Ghost127Jaws125Jurassic Park127Lethal Weapon110Michael106National Lampoon's Vacation98Poltergeist115Rocky120Scarface170Silence of the Lambs118Star Wars124The Hunt for Red October135The Terminator108The Wizard of Oz101Titanic194Movie mMediumShortShortLongOutput Delivery BasicsThe SAS Output Delivery System (ODS) provides many ways to format output. It controls the way output isaccessed and formatted. Although ODS continues to support the creation of traditional SAS listing or monospaceoutput (i.e., Listing), it provides many new features and greater flexibility when working with output.An early version of ODS appeared in Version 6.12 as a way to address the inherent weaknesses found in traditionalSAS output. It enables “quality” looking output to be produced without having to import it into word processors suchas MS-Word. In Version 8 and 9, many new output formatting features and options are introduced for SAS users totake advantage of. Users have a powerful and easy way to create and access formatted procedure and DATA stepoutput.Tip #7 – ODS and “Batch” UseMany of the ODS features found in the interactive side of the SAS Display Manager System (DMS) can also be usedin batch processing. ODS has been designed to make exciting new formatting options available to users. In awindowing environment, ODS can send output to the following destinations: the output window (DMS), the listing file,HTML, SAS dataset, rich text format (RTF), postscript file, external output file (non-SAS file), or output device. Theonly exception for batch processing is having output sent to the output window.Tip #8 – What if I’m Still Not Using the latest Version of SAS SoftwareFirst introduced in Version 6.12, ODS offered users the capability to format output to destinations other thantraditional line printers. Version 6.12 introduced the ability to deploy output to the web, the creation of SAS datasetsand rich text format (RTF) files, and DATA step interaction. ODS was designed to address the inherent weaknessesfound in traditional SAS output. It enables the creation of “quality” looking output without having to import it into wordprocessors such as MS-Word. New output enhancements were introduced in Version 8 and then in Version 9,including the ability to create postscript files and output customizations. To take full advantage of the power offered inODS, it is recommended that users upgrade to the latest Version as early as possible to take advantage of thesefeatures.