topic Re: Checking an array for not empty in SAS Programming

Checking an array for not empty

malena — Tue, 04 Apr 2017 14:36:09 GMT

I have a dataset of hospital discharges for 57 months (hd1-hd57) with character values (up to 20 in length) if there was a discharge. I want to select the records that have values. I wrote this code but it is not selecting all the records:

data kids_case;
set casemix_cancer;

array hd(57) cancer_HD1-cancer_HD57;

do i=1 to dim(hd);
date_hd=hd(i);
if missing(date_hd) then cancer_hd=0;
else cancer_hd=1;
end;

if cancer_hd=1;

run;

the data is in this format

id $20, cancer_HD1-cancer_HD57 $20

So, one record has id=XXHGG and only has 2 discharges: cancer_HD1=2345 and cancer_HD45=58414528. The rest of cancer_HD are blanks.

Re: Checking an array for not empty

RW9 — Tue, 04 Apr 2017 14:55:36 GMT

Post test data in the form of a datastep. This really helps illustrate your problem. At a guess, you could just concat the array and check for length?

if lengthn(cats(of hd_;)) > 0 then output;

I.e. if they are all blanks lengthn=0 so no output.

Re: Checking an array for not empty

ballardw — Tue, 04 Apr 2017 14:56:15 GMT

The code you have tests all values in the array. The value of cancer_hd is always going to be the result of the last comparison after the do loop.

If you want to set cancer_hd=1 when any of the values are set then perhaps this is what you want;

data kids_case;
   set casemix_cancer;
   array hd(57) cancer_HD1-cancer_HD57;
   do i=1 to dim(hd);
      date_hd=hd(i);
      if missing(date_hd) then cancer_hd=0;
      else do;
         cancer_hd=1;
         leave;
      end;
   end;
   if cancer_hd=1;
run;

The LEAVE statement says to quit the do loop when encountered. So this will interupt the loop the first time if finds a non-missing value.

Re: Checking an array for not empty

Tom — Tue, 04 Apr 2017 14:56:35 GMT

Your logic is flawed. You should set the flag to false before the loop and then in the loop set it to true if any non missing value is found. Your current code is effectly only testing the last value in the array.

But why not just use the CMISS() function to count how many variables have a missing value.

 cancer_hd = not (57 = cmiss(of cancerHD1-cancer_HD57));

Re: Checking an array for not empty

Astounding — Tue, 04 Apr 2017 14:56:51 GMT

Just to select the entire record, you could use:

data kids_case;

set casemix_cancer;

if cat(of cancer_hd1 - cancer_hd57) > ' ';

run;

If you are trying to take the existing records and find only the nonblank discharges, that would take a different approach.

Re: Checking an array for not empty

malena — Tue, 04 Apr 2017 15:20:42 GMT

thank you for all your suggestions! really appreciate it all your help