How to get the value of a particular row of a variable ?

[Siennayun]

If I have a column named “K” with 25 rows .
How can I add a new column DK[i]=K[i+1]+k[i-1] to the table?(when 2<i <25.)
I have no idea how to get the value of a particular row of a column.

Please give me some help

[ballardw]

It usually helps to indicate some data and what you expect the output for that given data to be.

Does your data set have 25 observations or are you asking to only process some observations out of a larger set?

[Kurt_Bremser]

For the value of K in the preceding observation, use the LAG() function; for the value in the following observation, use a look-ahead.

[Patrick · Accepted solution]

Below one way to go.

data have; 
  do k=1 to 25;
    output;
  end;
  stop;
run;

data want(drop=_k);
  merge have have(firstobs=2 keep=k rename=(k=_k));
  dk1=lag(k)+_k;
  dk2=sum(lag(k),_k);
run;

proc print data=want;
run;

[Siennayun]

Thank you so much for your help.
I’ve figured it out.