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1 Eliminate Cookie-Cutter Code with %wordLoop 1

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1 1 Eliminate Cookie-Cutter Code with %wordLoop 1

2 2 Def. of CCC – How It Is Created Write a short chunk of SAS code Write a short chunk of SAS code Copy, paste, edit Copy, paste, edit … (until the list in mind is exhausted) … (until the list in mind is exhausted)

3 3 Why diss Cookie-Cutter Code? 3 Now vs. later vs.

4 4 %wordLoop Signature %wordLoop( wordList=<>, contentMacro=<>); Where: wordList => values to loop over, e.g. data set names contentMacro => code applied on each loop

5 5 Example Code Select a subset of observations from each of N datasets Select a subset of observations from each of N datasets Create N new suitably-named datasets Create N new suitably-named datasets Subset specified by finderFileDs Subset specified by finderFileDs Why? subset analysis, data transfer, removal of patients from study Why? subset analysis, data transfer, removal of patients from study

6 6 Example Cookie-Cutter Code DATA patientDs_subset; MERGE patientDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA consultDs_subset; MERGE consultDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA hospStayDs_subset; MERGE hospStayDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA eventsDs_subset; MERGE eventsDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA drugsDs_subset; MERGE drugsDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN;

7 7 Ex. CCC showing Substitutions DATA patientDs_subset; MERGE patientDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA consultDs_subset; MERGE consultDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA hospStayDs_subset; MERGE hospStayDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA eventsDs_subset; MERGE eventsDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN; DATA drugsDs_subset; MERGE drugsDs(in=in1) finderFileDs(in=in2);BY id; IF in1 and in2; RUN;

8 8 Repeating Pattern Repeating Pattern DATA _subset; MERGE (in=in1) finderFileDs(in=in2); BY id; IF in1 and in2; RUN; Ds list: patientDs consultDs hospStayDs eventDs drugDs

9 9 Liabilities of CCC Cut-paste-edit errors Cut-paste-edit errors Bulky and hard to read Bulky and hard to read Tedious to change implementation Tedious to change implementation List is hidden List is hidden List tedious to change List tedious to change Make a macro of repeating element?

10 10 Ex. with Macro Definition Ex. with Macro Definition %MACRO getSubset(ofDs=); DATA &ofDs._subset; MERGE &ofDs(in=in1) finderFileDs (in=in2); BY id; IF in1 and in2; RUN; %MEND; %getSubset(ofDs=patientDs ); %getSubset(ofDs=consultDs ); %getSubset(ofDs=hospStayDs); %getSubset(ofDs=eventsDs ); %getSubset(ofDs=drugsDs ); Still got cookies! Still list elements are dispersed.

11 11 Ex. with %wordLoop %MACRO getSubset( ); DATA &word._subset; MERGE &word.(in=in1) finderFileDs(in=in2); BY id; IF in1 and in2; RUN; %MEND; %LET ds=patientDs consultDs hospStayDs eventsDs drugsDs ; %wordLoop(wordList=&ds,contentMacro=getSubset( )); Oops! What about sort order?

12 12 Again with sort %MACRO getSubset(); proc sort DATA=&word; BY id; RUN; DATA &word._subset; MERGE &word.(in=in1) finderFileDs(in=in2); BY id; IF in1 and in2; RUN; %MEND; %LET ds=patientDs consultDs hospStayDs eventsDs drugsDs; %wordLoop(wordList=&ds,contentMacro=getSubset( )); SQL better?

13 13 Again with SQL %MACRO getSubset(); PROC sql; create table &word._subset as select * from &word, finderFileDs where &word..id = finderFileDs.id; QUIT; %MEND; %LET ds=patientDs consultDs hospStayDs eventsDs drugsDs; %wordLoop(wordList=&ds,contentMacro=getSubset( )); Change localized!

14 14 %wordLoop code %MACRO wordLoop(wordList=, contentMacro=); %LOCAL word cnt; %LET cnt=0; %DO %WHILE(1 eq 1); %LET cnt = %eval(&cnt+1); %LET word= %scan(&wordList, &cnt, %str( )); %IF &word= %THEN %RETURN; %&contentMacro; %END; %MEND wordLoop; ContentMacro must not %LOCAL word!

15 15 Example 2 Code Recode 99 to “.” for selected variables Recode 99 to “.” for selected variables 5 variables need to be recoded 5 variables need to be recoded 3 variables might have valid 99s 3 variables might have valid 99s CCC occurs within a DATA step CCC occurs within a DATA step

16 16 Ex. 2 Cookie-Cutter Code DATA data99sFixed; SETdataWith99sDs; IF eyeColor eq 99 THEN eyeColor =.; IF hairColor eq 99 THEN hairColor =.; IF bloodtype eq 99 THEN bloodtype =.; IF prevCardiac eq 99 THEN prevCardiac =.; IF prevCancer eq 99 THEN prevCancer =.; RUN;

17 17 Ex. 2 with Array Solution %LET varsWith99 = eyeColor hairColor bloodtype prevCardiac prevCancer; DATA data99sFixedDs; SET dataWith99sDs; ARRAY vars99arr{*} &varsWith99; DO i=1 to dim(vars99arr); IF vars99arr(i) eq 99 THEN vars99arr(i) =.; END; DROP i; RUN; This works but so does …

18 18 Ex. 2 with %wordLoop %LET varsWith99 = eyeColor hairColor bloodtype prevCardiac prevCancer; %MACRO cnvt99s(); IF &word eq 99 THEN &word=.; %MEND; DATA data99sFixed; SETdataWith99sDs; %wordLoop(wordList=&varsWith99, contentMacro=cnvt99s()); RUN;

19 19 Misuses of %wordLoop Avoid use with datasets representing partitions of DATA (e.g. sites) Avoid use with datasets representing partitions of DATA (e.g. sites) Combine and processBY site, instead Combine and processBY site, instead Avoid use with procs whenBY or CLASS can be used (e.g. PROC MEANS) Avoid use with procs whenBY or CLASS can be used (e.g. PROC MEANS)

20 20 Take Aways Avoid cookie-cutter-code! Avoid cookie-cutter-code! %wordLoop() can help you do this %wordLoop() can help you do this SAS macros allow you to adapt the SAS language to your purposes. SAS macros allow you to adapt the SAS language to your purposes.

21 21 Big Picture Illustrate and define cookie-cutter code Illustrate and define cookie-cutter code Discuss the liabilities of same Discuss the liabilities of same Present the user view of %wordLoop Present the user view of %wordLoop Use it to eliminate the cookie-cutter code Use it to eliminate the cookie-cutter code %wordLoop implementation %wordLoop implementation


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