carrying forward values

[bgosiker]

Hi everyone, 

I have a long dataset and some missingness in my data. For places where there are some gaps in data I was wanting to carry forward the most recent value a maximum of TWO times. I have this code that carries forward the value of smokestat until the next non-missing value of smokestat, but I don't want it to carry it forward that far. I was having some issues adapting this code to only carry it forward a maximum of two visits. Any help appreciated!

data Aim2.Final; set Aim2.Final;
	 n=_n_;
	 if missing(smokestat) then do;
	   do until (not missing(smokestat));
	     n=n-1;
	     set Aim2.Final(keep=smokestat) point=n;  
	   end;
	 end;
run;

Hi everyone, 

[Astounding · Accepted solution]

A reasonable approach:

data want;
   set have;
   retain n replacement;
   if smokestat > . then do;
      replacement = smokestat;
      n = 0;
   end;
   else do;
      n + 1;
      smokestat = replacement;
      if n = 2 then call missing(replacement);
   end;
run;