topic Making ID variable without any other information in SAS Programming

Making ID variable without any other information

tbanh — Wed, 17 Oct 2018 03:37:12 GMT

Hello,

I'm having trouble creating an ID variable because there are no other variables in the data set for me to use the first.variable trick to create an ID variable. Here is a description of the data. The labels Response_1 through Response_N represent repeated measurements for individuals. I would like to create for the first 12 lines, ID = 1 and for the next 12 lines, ID = 2 all the way until ID = 228. The variable Iter represents the iteration number for this simulated data.

Please let me know if there's anything I can do to clarify what I did. Thank you

-Tim

Re: Making ID variable without any other information

Tom — Wed, 17 Oct 2018 04:10:43 GMT

Can't you just use arithmetic to make the new variable?

data want ;
  id = 1+int((_n_-1)/12);
  set have ;
run;

Re: Making ID variable without any other information

Criptic — Wed, 17 Oct 2018 08:21:09 GMT

I'm not quite sure I completly get what you are trying to say - Are you saying you want an the same ID for the first 12 Lines and after that keep increasing the id - if so:

data work.aa1;
 set your_input;
 if _n_ lt 13 then id eq 1;
 else id = id + 1;
 retain id;
run;

If you always have 12 responses than you could to something like this - using the mod function

data work.aa2;
 set your_input;
 if _n_ eq 1 then id eq 1;
 else if mod(_n_,13) eq 0 then id = id + 1;
 retain id;
run;

Or if you need a new id every line

data work.aa3;
 set your_input;
 id = _n_;
run;

Re: Making ID variable without any other information

tbanh — Wed, 17 Oct 2018 17:34:47 GMT

This works! Thank you so much Tom. One more question. Per each iteration, I have 228 subjects. The code you provided works for the first iteration but for Iter = 2, as you can see in the picture, SUBID starts back at 1, which I would like, but it does not repeat the same procedure as for Iter = 1. Here is the code I used to generate the data:

data long2;
  set long1;
  SUBID = 1 + int((_n_-1)/12);
  by Iter; 
  if first.Iter then SUBID = 1;
run;

Re: Making ID variable without any other information

Tom — Wed, 17 Oct 2018 18:21:11 GMT

Keep your own counter per ITER instead of use the automatic _N_ variable.

row+1; 
if first.ITER then row=1;

Or you can use a DO Loop around the SET statement, note that means you need to add an OUTPUT statement.

data long2;
do row=1 by 1 until(last.Iter);
  set long1;
  by Iter; 
  SUBID = 1 + int((ROW-1)/12);
  output;
end;
run;

Or better just use two DO loops.

data long2;
do SUBJID=1 by 1 until(last.iter);
  do row=1 to 12 until(last.Iter);
    set long1;
    by Iter; 
    output;
  end;
end;
run;