id x
1 2
2 3
3 5
4 8
5 9
6 8
hi, i have sample dataset like above. i want to create a new variable y, such that,
if id = 1, then y = x;
else y(t)= y(t-1) * 2.
in this case:
y(1) = x(1) = 2
y(2) = y(1) *2 = 2*2 = 4
y(3) =y(2) *2 = 4*2 = 8
y(4) =y(3) *2 = 8*2 = 16
y(5) = y(4) *2 = 16*2 = 32
y(6) = y(5) *2 = 32*2 = 64
i am wondering if there is any function to achieve it? looks like lag can't do it.
thanks a lot for your help!
Hi, you can try this method. You are right, LAG function can't do it.
data test;
input id x;
retain temp;
if id=1 then do;
y=x;
temp=y;
end;
if id ne 1 then do;
y=temp*2;
temp=y;
end;
drop temp;
cards;
1 2
2 3
3 5
4 8
5 9
6 8
;
run;
Hi, you can try this method. You are right, LAG function can't do it.
data test;
input id x;
retain temp;
if id=1 then do;
y=x;
temp=y;
end;
if id ne 1 then do;
y=temp*2;
temp=y;
end;
drop temp;
cards;
1 2
2 3
3 5
4 8
5 9
6 8
;
run;
Smart! thank you!
You can simplify the code a bit.
data test;
input id x;
retain y;
y=ifn(id=1,x,y*2);
cards;
1 2
2 3
3 5
4 8
5 9
6 8
;
run;
Thanks Keith, works better!
Year, this is easier.
Join us for SAS Innovate April 16-19 at the Aria in Las Vegas. Bring the team and save big with our group pricing for a limited time only.
Pre-conference courses and tutorials are filling up fast and are always a sellout. Register today to reserve your seat.
Learn the difference between classical and Bayesian statistical approaches and see a few PROC examples to perform Bayesian analysis in this video.
Find more tutorials on the SAS Users YouTube channel.