How to make a variable to be '1' if it is the first instance of a new variable in a by group?

Tom_87 — Sat, 22 Mar 2014 18:23:37 GMT

See the title and the attached file. How do I write the SAS code to create variable 3? I am not very experienced with SAS, so any help would be greatly appreciated. Thank you!

Edit- Thank you Bruno, that worked perfectly!

Re: How to make a variable to be '1' if it is the first instance of a new variable in a by group?

BrunoMueller — Sat, 22 Mar 2014 22:07:17 GMT

Assuming the input data is sorted by var_1, then the following code should do what you want:

data want;
  set have;
  by Var_1;
  if first.var_1 = 1 then do; 
    retain checkForA;
    checkForA = 1; 
  end; 
  if checkForA = 1 and var_2 = "A" then do; 
    var_3_sas = 1; 
    checkForA = 0; 
  end; 
  var_3_sas = coalesce(var_3_sas, 0);
run;

topic How to make a variable to be '1' if it is the first instance of a new variable in a by group? in SAS Programming

How to make a variable to be '1' if it is the first instance of a new variable in a by group?

Re: How to make a variable to be '1' if it is the first instance of a new variable in a by group?