first. and last. statement within groups

[AndreasKirk]

Is it possible to use the first. and last. statement within certain groups?

E.g. I have a variable with social security numbers and a variable with years. I have multiple person records each year. I would like to use the first. statement to identify the first observation of each social security number, but for each year. Is this possible?

[jakarman]

Short answer: yes ....

SAS(R) 9.3 Language Reference: Concepts, Second Edition (How the DATA Step Identifies BY Groups)

An example is mot easy found bit it works (long time ago remembering having done)

[SteffenBille]

Data out;

set in;

by social_security_number year;

first.name then output;

run;

[RichardinOz · Accepted solution]

Corrected version

Data out;

     set in;

     by social_security_number year;

     if first.year then output;

run;

Explanation

You can have numerous by variables, and for each one first and last automatic variables are generated.

In this case first.social_security_number would return only one record per social_security_number.  First.year is updated every time there is a change in the preceding by variable(s) as well as when there is a change in year.

Richard