topic need 'min' function to return variable name and not observation values in SAS Procedures

need 'min' function to return variable name and not observation values

michele — Tue, 16 Aug 2011 11:03:14 GMT

Hi everybody! I am new here, I am a doctor and I use SAS to perform basic stat analysis. Right now I am having trouble editing a dataset, I am not sure how to solve the problem but I know there must be an easy way to do it, so I am asking for your help

This is a sample of my dataset

id exam1 exam2 exam3 exam4

1 1999 2007 2003 2000

2 2009 1985 2004 2001

3 2000 2001 2002 2003

What I want to do: to create a new variable 'firstexam' in which i have the name of the first exam and not the actual date

my new dataset should be like this:

id ... firstexam

1 exam1

2 exam2

3 exam1

if i use the min function I get

id ... firstexam

1 1999

2 1985

3 2000

I know I could do it with a bunch of 'if' and 'then' but the editor would be so long and ugly.. I am sure there is an easier way to get the job done...

Thanks a lot!

need 'min' function to return variable name and not observation values

MichelleHomes — Tue, 16 Aug 2011 11:46:43 GMT

Hi Michele,

I haven't tested this but I think it might be what you are after... use the vname function around your min function...

firstexam = vname(min(exam1, exam2, exam3, exam4));

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000202943.htm

Hope this helps.

Cheers,

Michelle

need 'min' function to return variable name and not observation values

art297 — Tue, 16 Aug 2011 12:49:40 GMT

I think you are looking for something like:

data have;

input id exam1 exam2 exam3 exam4;

array years(*) exam1-exam4;

firstexam=vname(years[whichn(min(of years(*)), of years

)]);

cards;

1 1999 2007 2003 2000

2 2009 1985 2004 2001

3 2000 2001 2002 2003

;

run;

proc print;

run;

need 'min' function to return variable name and not observation values

Howles — Tue, 16 Aug 2011 15:08:44 GMT

Are ties possible (2 or more tests in the earliest year for an ID)? If so, what should materialize in FIRSTEXAM?

need 'min' function to return variable name and not observation values

michele — Tue, 16 Aug 2011 18:10:22 GMT

Thanks everyone.

Ties will not be possible, as the date would actually be composed of year-month-day, I have only put years to simplify it.

I will try the array+vname approach as soon as I can and I will let you know.

need 'min' function to return variable name and not observation values

art297 — Tue, 16 Aug 2011 21:06:05 GMT

You don't have to change anything in the code .. you just have to ensure that your date fields were in fact read in as SAS dates.

Years is simply the name I assigned to the array, thus you don't really have to change it. If you do want it to reflect something else, make sure that you change it in all four instances where it is used.