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?
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
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)
Data out;
set in;
by social_security_number year;
first.name then output;
run;
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
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