topic Re: Do loop iteration to rename variables... in SAS Programming

Do loop iteration to rename variables...

gstullo — Mon, 02 Dec 2013 21:54:48 GMT

I'm sure that this is simple but I'm new to loops and iterations. After spending hours getting nowhere I figured I'd try here.

I would like to rename a set of variables as follows

ExampleA = ExampleA1;

ExampleB = ExampleB1;

output;

But I want the above to do this for 1-9.

easy enough to just copy and change the final number manually but is really like to use a loop or Marco or something...

Any thoughts?

Thanks

Re: Do loop iteration to rename variables...

Astounding — Mon, 02 Dec 2013 22:11:44 GMT

I think you are saying that you have 18 existing variables:

ExampleA1 ... ExampleA9

ExampleB1 ... ExampleB9

And you would like to change them into 9 observations with just 2 variables on each observation. If that's the problem you're trying to solve, this would be a viable approach:

data want;

set have;

array a {9} ExampleA1 - ExampleA9;

array b {9} ExampleB1 - ExampleB9;

do _n_=1 to 9;

ExampleA = a{_n_};

ExampleB = b{_n_};

output;

end;

keep ExampleA ExampleB;

run;

Of course, if you're trying to accomplish something different, that's another story.

Good luck.

Re: Do loop iteration to rename variables...

twocanbazza — Mon, 02 Dec 2013 22:18:25 GMT

I think you need to explain the desire results a little better...

However simple do loop (needs to be enclosed in a Macro and data step)

%do i=1 %to 9 ;

ExampleB&i. = ExampleA&i. ;

%end;

From a simple google "http://support.sas.com/resources/papers/proceedings11/113-2011.pdf"

Re: Do loop iteration to rename variables...

gstullo — Tue, 03 Dec 2013 02:18:29 GMT

Thanks for the tip.

I had read that article and, at first thought that my leaving the "." out after the "i" was causing this not to work. With or without the period, I was getting the same result of 176 observations instead of the expected 848. I finally noticed that my output statement was outside of the Do loop rather than within it which created the missing observation problem. Once I fixed that, I got the expected results.

To answer your question, user Astounding was correct in assuming that I had several variables 1-5 (not 9) that I wanted condensed. My initial code worked fine but the Macro version is shorter less error prone. I've posted the initial code followed by the working macro version:

INITIAL (obnoxiously long) CODE:

data Log (keep=SubjectID VisitDate Initials Age TeamReferred SelfReferred PfPositive PfDensity EpisodeNumber Antimalarials Comments);

set data9;

SubjectId=MalariaLogID1;

VisitDate=MalariaEpisodeDate1;

Initials=PatientInitials1;

Age=PatientAge1;

TeamReferred=ReferredByStudyTeam1;

SelfReferred=SelfReferral1;

PfPositive=PfPositive1;

PfDensity=PfDens1;

EpisodeNumber=EpisodeNumber1;

Antimalarials=AntimalarialProvided1;

Comments=Comments1;

output;

SubjectId=MalariaLogID2;

VisitDate=MalariaEpisodeDate2;

Initials=PatientInitials2;

Age=PatientAge2;

TeamReferred=ReferredByStudyTeam2;

SelfReferred=SelfReferral2;

PfPositive=PfPositive2;

PfDensity=PfDens2;

EpisodeNumber=EpisodeNumber2;

Antimalarials=AntimalarialProvided2;

Comments=Comments2;

output;

SubjectId=MalariaLogID3;

VisitDate=MalariaEpisodeDate3;

Initials=PatientInitials3;

Age=PatientAge3;

TeamReferred=ReferredByStudyTeam3;

SelfReferred=SelfReferral3;

PfPositive=PfPositive3;

PfDensity=PfDens3;

EpisodeNumber=EpisodeNumber3;

Antimalarials=AntimalarialProvided3;

Comments=Comments3;

output;

SubjectId=MalariaLogID4;

VisitDate=MalariaEpisodeDate4;

Initials=PatientInitials4;

Age=PatientAge4;

TeamReferred=ReferredByStudyTeam4;

SelfReferred=SelfReferral4;

PfPositive=PfPositive4;

PfDensity=PfDens4;

EpisodeNumber=EpisodeNumber4;

Antimalarials=AntimalarialProvided4;

Comments=Comments4;

output;

SubjectId=MalariaLogID5;

VisitDate=MalariaEpisodeDate5;

Initials=PatientInitials5;

Age=PatientAge5;

TeamReferred=ReferredByStudyTeam5;

SelfReferred=SelfReferral5;

PfPositive=PfPositive5;

PfDensity=PfDens5;

EpisodeNumber=EpisodeNumber5;

Antimalarials=AntimalarialProvided5;

Comments=Comments5;

output;

format VisitDate MMDDYY10.;

format SubjectID ML_format.;

run;

data Log;

set Log;

if SubjectID="" then delete;

run;

proc sort data=Log;

by SubjectID;

run;

SHORT MACRO VERSION:

%macro MacroTest;

data MacroTest (keep=SubjectID VisitDate Initials Age TeamReferred SelfReferred

PfPositive PfDensity EpisodeNumber Antimalarials Comments);

set data9;

%DO i = 1 %to 5;

SubjectId=MalariaLogID&i;

VisitDate=MalariaEpisodeDate&i;

Initials=PatientInitials&i;

Age=PatientAge&i;

TeamReferred=ReferredByStudyTeam&i;

SelfReferred=SelfReferral&i;

PfPositive=PfPositive&i;

PfDensity=PfDens&i;

EpisodeNumber=EpisodeNumber&i;

Antimalarials=AntimalarialProvided&i;

Comments=Comments&i;

output;

%end;

format VisitDate MMDDYY10.;

format SubjectID ML_format.;

run;

data MacroTest;

set MacroTest;

if SubjectID="" then delete;

run;

proc sort data=MacroTest;

by SubjectID;

run;

%Mend MacroTest;

Re: Do loop iteration to rename variables...

gstullo — Tue, 03 Dec 2013 02:23:46 GMT

Thanks for the reply. You stated my intention correctly.

I came up with the following which gave me what I wanted though I found it slightly more cumbersome to program. If you would no mind having a look at this as well as the Macro version that I posted in reply to Barry and letting me know if you see a benefit to one version over another, I'd appreciate it.

This was great though as I've been meaning to learn arrays. I'll be dissecting this and learning how it works tomorrow:

data ArrayTest (keep=SubjectID VisitDate Initials Age TeamReferred SelfReferred

PfPositive PfDensity EpisodeNumber Antimalarials Comments);

set data9;

array a {5} MalariaLogID1-MalariaLogID5;

array b {5} MalariaEpisodeDate1-MalariaEpisodeDate5;

array c {5} PatientInitials1-PatientInitials5;

array d {5} PatientAge1-PatientAge5;

array e {5} ReferredByStudyTeam1-ReferredByStudyTeam5;

array f {5} SelfReferral1-SelfReferral5;

array g {5} PfPositive1-PfPositive5;

array h {5} PfDens1-PfDens5;

array i {5} EpisodeNumber1-EpisodeNumber5;

array j {5} AntimalarialProvided1-AntimalarialProvided5;

array k {5} Comments1-Comments5;

do n =1 to 5;

SubjectID=a{n};

VisitDate=b{n};

Initials=c{n};

Age=d{n};

TeamReferred=e{n};

SelfReferred=f{n};

PfPositive=g{n};

PfDensity=h{n};

EpisodeNumber=i{n};

Antimalarials=j{n};

Comments=k{n};

output;

format VisitDate MMDDYY10.;

format SubjectID ML_format.;

run;

data ArrayTest;

set ArrayTest;

if SubjectID="" then delete;

run;

proc sort data=Arraytest;

by SubjectID;

run;