data logic

[Almoha]

Hi All

I have the following data set and I want to populate ‘x’  for every 3^rd  observation  and “Y”  for the 4^th observation in Res variable

ID	Res
111	x
222	x
333	x
444	y
555	x
666	x
777	x
888	y
…..

Any pointers?

Thanks

Al

[Reeza]

Look at the MOD function in combination with the _N_ automatic variable. 

flag='X';
if mod(_n_, 4) =0 then flag='Y';